2015年01月, 日本化学会北海道支部, 奨励賞　　　　　　　　　　　　　　　
鱒渕友治

2012年06月, 日本セラミックス協会, 日本セラミックス協会賞進歩賞　　　　　　　　　　　　　　　
鱒渕友治

Average Cubic BaTaO₂N Crystal Structure Formed by 50 nm Size Domains with Polar Nanoregions Consisting of cis-TaO₄N₂ Octahedral Chains
Yuji Masubuchi, Kyohei Koyama, Akira Hosono, Mikio Higuchi, Masaki Takesada, Kazuki Shitara, Hiroki Moriwake, Shinichi Kikkawa
Chemistry of Materials, American Chemical Society (ACS), 2024年07月29日
研究論文（学術雑誌）

Preparation of TaON thin films by nitridation of solution process-derived precursor films with urea
Amon Higuchi, Nataly Carolina Rosero-Navarro, Akira Miura, Yuji Masubuchi, Kiyoharu Tadanaga
Journal of Sol-Gel Science and Technology, Springer Science and Business Media LLC, 2024年06月27日
研究論文（学術雑誌）

Mechanical Properties of Modulative Undulating Layers in Two-Dimensional Metal–Organic Frameworks
Yuudai Iwai, Sotaro Kusumoto, Ryo Suzuki, Masaru Tachibana, Kazuki Komatsu, Takashi Kikuchi, Saori I. Kawaguchi, Hirokazu Kadobayashi, Yuji Masubuchi, Yuzuki Yamamoto, Yoshiki Ozawa, Masaaki Abe, Kenji Hirai, Benjamin Le Ouay, Masaaki Ohba, Ryo Ohtani
Chemistry of Materials, American Chemical Society (ACS), 2024年05月21日
研究論文（学術雑誌）

Nitrogen-Rich Molybdenum Nitride Synthesized in a Crucible under Air
Momoka Demura, Masanori Nagao, Chul-Ho Lee, Yosuke Goto, Yusuke Nambu, Maxim Avdeev, Yuji Masubuchi, Takato Mitsudome, Wenhao Sun, Kiyoharu Tadanaga, Akira Miura
Inorganic Chemistry, 2024年03月18日
研究論文（学術雑誌）

Novel synthetic approaches and morphological design of perovskite-type oxynitrides in powder and ceramic form
Yuji Masubuchi
Progress in Solid State Chemistry, 73, 2024年03月
研究論文（学術雑誌）, Perovskite-type oxynitrides are a new class of inorganic materials that have potential applications as photocatalysts, inorganic pigments and dielectrics. Design of the morphology in conjunction with new synthesis methods is essential for their practical use. In this review, we present the formation of fine particles via a low temperature and ammonia-free synthesis method, the morphology of the oxynitride perovskites obtained using metal carbodiimide, and the toughness of the sintered ceramics in relation to their microstructure.

Effect of BaCl2 flux on low temperature synthesis of Ba3Si6O12N2:Eu phosphors from BaCN2 and SiO2.
Hiroshi Shibuya, Yuji Masubuchi, Mikio Higuchi
Journal of the Ceramic Society of Japan, 131, 9, 565, 568, Ceramic Society of Japan, 2023年09月01日, ［査読有り］, ［責任著者］
研究論文（学術雑誌）

Ferroelectric BaTaO2N perovskite — Towards structure-property relationship study on high-quality crystals and ceramics prepared with the aid of liquid phase
Akira Hosono, Yuji Masubuchi, Mikio Higuchi, Shinichi Kikkawa
Solid State Sciences, 144, 107310, 107310, Elsevier BV, 2023年09月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）

Temperature dependence of luminescence color of Mn2+-doped ZnCN2 phosphor
Akane Wakabayashi, Yuji Masubuchi, Mikio Higuchi, Jumpei Ueda, Setsuhisa Tanabe
Materials Letters, 346, 134555, 134555, Elsevier BV, 2023年09月, ［査読有り］, ［責任著者］
研究論文（学術雑誌）

Preparation of thick dense ceramic films of dielectric BaTaO2N through electrophoretic deposition
Hiroto Takeuchi, Daiki Miyamoto, Yuji Masubuchi, Mikio Higuchi, Kento Ishii, Tetsuo Uchikoshi
Ceramics International, 46, 21825, 21829, Elsevier {BV}, 2023年07月, ［査読有り］, ［責任著者］
英語, 研究論文（学術雑誌）

High-pressure phases of BaCN2 explored using a genetic algorithm
Peng Song, Mari Khawaguch, Yuji Masubuchi, Kenji Oqmhula, Kousuke Nakano, Ryo Maezono, Kenta Hongo
COMPUTATIONAL MATERIALS SCIENCE, 226, 134555/1, 134555/3, ELSEVIER, 2023年06月, ［査読有り］
英語, 研究論文（学術雑誌）, Nitrogen-containing polymers have attracted considerable research attention for their application to high energy density materials, where the energy is internally stored in their triple bonds. In this regard, it is intriguing to examine whether such polymerized phases appear in the high-pressure phase of metal carbodiimide MCN2, which have been synthesized recently. However, very few studies have investigated crystal structures up to 10/15 GPa in experiments/simulations. In this work, we adopted a structure search based on genetic algorithm coupled with ab initio electronic structure calculations to investigate possible crystal structures that may appear in the high-pressure phase of BaCN2. Furthermore, we reproduced the previously reported crystal structures in the lower pressure range similar to 6 GPa. With confirmed reliability of its predictive capability, we used the genetic search and predicted a polymerized phase with Ima2 appearing at higher pressure above 42 GPa. The polymerized phase has a linear network structure of CN3 planar triangular units. It has been found that the anion site units CN2, which are close to each other under high pressure, form direct covalent bonds and stabilize the phase.

Enhanced NH3 Sensing Performance of Mo Cluster-MoS2 Nanocomposite Thin Films via the Sulfurization of Mo-6 Cluster Iodides Precursor
Meiqi Zhang, Fabien Grasset, Yuji Masubuchi, Toshihiro Shimada, Thi Kim Ngan Nguyen, Noee Dumait, Adele Renaud, Stephane Cordier, David Berthebaud, Jean-Francois Halet, Tetsuo Uchikoshi
NANOMATERIALS, 13, 3, MDPI, 2023年02月
英語, 研究論文（学術雑誌）, The high-performance defect-rich MoS2 dominated by sulfur vacancies as well as Mo-rich environments have been extensively studied in many fields, such as nitrogen reduction reactions, hydrogen evolution reactions, as well as sensing devices for NH3, which are attributed to the under-coordinated Mo atoms playing a significant role as catalytic sites in the defect area. In this study, the Mo cluster-MoS2 composite was creatively synthesized through a one-step sulfurization process via H-2/H2S gas flow. The Mo-6 cluster iodides (MIs) coated on the fluorine-doped tin oxide (FTO) glass substrate via the electrophoretic deposition method (i.e., MI@FTO) were used as a precursor to form a thin-film nanocomposite. Investigations into the structure, reaction mechanism, and NH3 gas sensing performance were carried out in detail. The results indicated that during the gas flowing, the decomposed Mo-6 cluster iodides played the role of template and precursor, forming complicated Mo cluster compounds and eventually producing MoS2. These Mo cluster-MoS2 thin-film nanocomposites were fabricated and applied as gas sensors for the first time. It turns out that after the sulfurization process, the response of MI@FTO for NH3 gas increased three times while showing conversion from p-type to n-type semiconductor, which enhances their possibilities for future device applications.

Spectral properties and β-ray scintillation of GdVO4:Eu single crystals grown by the floating zone method
Minori Matsuoka, Mikio Higuchi, Fumihiko Nishikido, Taiga Yamaya, Takashi Takeda, Yuji Masubuchi, Junichi H. Kaneko
Journal of Luminescence, 251, 119208, 119208, 2022年11月, ［査読有り］
英語, 研究論文（学術雑誌）, GdVO4:Eu single crystals were successfully grown along the [110] direction by the floating zone method. The grown crystals had no cracks and inclusions for any Eu-concentration. The polarizing microscopy proved that the grown crystal contained no microscopic defects such as low-angle grain boundaries and inclusions. The crystal showed red fluorescence with the peak wavelength of 620 nm. The emission showed strong polarization dependence; the emission of π-polarization is more intensive than that of strongly the σ-polarization. Under irradiation of X-ray or electron beam, the crystals also showed strong red fluorescence based on the host excitation. The fluorescence lifetime was measured to be about 785 μs. Scintillation the GdVO4:Eu single crystals for β-ray was successfully demonstrated using nuclear medicine 18F-fludeoxyglucose.

High-pressure behavior of tetragonal barium carbodiimide, BaNCN
Yuji Masubuchi, Suzuka Miyazaki, Peng Song, Takafumi Yamamoto, Kosuke Nakano, Kenta Hongo, Ryo Maezono
JOURNAL OF ALLOYS AND COMPOUNDS, 918, ELSEVIER SCIENCE SA, 2022年10月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, The high-pressure behavior of tetragonal barium carbodiimide (BaNCN) was investigated by in-situ highpressure X-ray diffraction measurements and first-principles theoretical calculations. No phase transition or decomposition of tetragonal BaNCN was observed during compression to 6.0 GPa and subsequent decompression to ambient pressure. The bulk modulus estimated from the unit cell volume with respect to the applied pressure was 69(2) GPa, which is comparable to that estimated by first-principles calculations. The theoretical calculations indicate that contraction of the Ba-N bond length has a crucial effect on the volume change in response to pressure, whereas the C-N bonds in the NCN2-anions remain robust against the change in pressure. (C) 2022 Published by Elsevier B.V., 32220525

Non-ammonolysis synthesis and characterisation of environmentally benign yellow pigments based on calcium–tantalum perovskite oxynitrides
Takuya Sakata, Sohta Urushidani, Naoki Tarutani, Kiyofumi Katagiri, Kei Inumaru, Kyohei Koyama, Nozomu Iwata, Yuji Masubuchi
Materials Advances, 3, 4899, 4907, Royal Society of Chemistry ({RSC}), 2022年05月, ［査読有り］
英語, 研究論文（学術雑誌）, 32220525

B2O3 as a new sintering additive for perovskite-type SrTaO2N oxynitride ceramics
Yuji Masubuchi, Daiki Miyamoto, Mikio Higuchi
Journal of Asian Ceramic Societies, 10, 1, 158, 164, Informa {UK} Limited, 2022年01月02日, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌）, 32220525

Effect of polyols on membrane structures of liposomes: A study using small-angle X-ray scattering data and generalized indirect Fourier transformation
Sekine, A., Ogura, T., Tsuchiya, K., Ohishi, K., Masubuchi, Y., Akamatsu, M., Sakai, K., Abe, M., Sakai, H.
Chemistry and Physics of Lipids, 249, 2022年
研究論文（学術雑誌）

固体窒素源を利用した安全・サステナブルな金属酸窒化物合成法の開発
片桐清文, 坂田拓也, 樽谷直紀, 鱒渕友治
Fine Ceramics Report, 40, 2, 2022年

Heteroepitaxial Growth of a Ta3N5 Thin Film with Clear Anisotropic Optical Properties
Yannan Wang, Yasushi Hirose, Takuto Wakasugi, Yuji Masubuchi, Masato Tsuchii, Yuki Sugisawa, Daiichiro Sekiba, Akira Chikamatsu, Tetsuya Hasegawa
The Journal of Physical Chemistry Letters, 12323, 12328, American Chemical Society (ACS), 2021年12月22日, ［査読有り］
研究論文（学術雑誌）, 32220525

Solving the puzzle of the dielectric nature of tantalum oxynitride perovskites
Shinichi Kikkawa, Yuji Masubuchi
Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences, 76, 10-12, 543, 545, 2021年11月01日
研究論文（学術雑誌）, The dielectric properties of tantalum oxynitride perovskites are of interest because of the unique optical characteristics of these compounds based on their visible light absorption. Unfortunately, such perovskites are thermally metastable, which makes it challenging to prepare high-quality bulk samples for the study of dielectric properties. Recently, studies of small single crystals of BaTaO2N showed the compound to be ferroelectric, and this can be well explained based on the non-centrosymmetric crystal structure proposed previously using first-principles and molecular dynamic investigations.

Low temperature synthesis of barium oxynitridosilicates using BaCN2 and SiO2
Yuji Masubuchi, Naoki Sada, Yoshiteru Kawahara, Kenji Arai, Teruki Motohashi, Mikio Higuchi
DALTON TRANSACTIONS, 50, 17, 5883, 5889, ROYAL SOC CHEMISTRY, 2021年05月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Barium oxynitridosilicates, Ba3Si6O12N2 and Ba3Si6O9N4, were obtained from a mixture of BaCN2 and SiO2 at 800 degrees C, which is several hundred degrees lower than the temperature required in solid state reactions using BaCO3, SiO2 and Si3N4. The low-temperature formation mechanism was investigated by thermogravimetry analysis in conjunction with gas chromatography and mass spectroscopy. The phase ratio between the oxynitridosilicates was controlled by tuning the reaction temperature, duration, and atmosphere. Almost single-phase Ba3Si6O12N2 was obtained by reaction at 800 degrees C for 15 h under a N-2 atmosphere, but the product changed to Ba3Si6O9N4 after 50 h at 800 degrees C or by heating at 950 degrees C for 15 h. The photoluminescence properties of Eu-doped products obtained at 800 degrees C using a mixture of BaCN2 : Eu and SiO2 were investigated., 32220525

Ternary carbodiimide compound, Ba0.9Sr0.1NCN with distorted rutile-type structure
Yuji Masubuchi, Suzuka Miyazaki, Kotaro Fujii, Masatomo Yashima, Akira Miura, Mikio Higuchi
Journal of Solid State Chemistry, 296, 122000, 122000, Elsevier BV, 2021年04月, ［査読有り］, ［招待有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌）, 32220525

Environmentally Benign Synthesis and Color Tuning of Strontium-Tantalum Perovskite Oxynitride and Its Solid Solutions
Takuya Sakata, Risa Yoshiyuki, Ryoki Okada, Sohta Urushidani, Naoki Tarutani, Kiyofumi Katagiri, Kei Inumaru, Kyohei Koyama, Yuji Masubuchi
INORGANIC CHEMISTRY, 60, 7, 4852, 4859, AMER CHEMICAL SOC, 2021年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, A facile method was successfully developed to prepare strontium-tantalum perovskite oxynitride, SrTaO2N, and its solid solutions. Urea was employed as a solid nitriding agent to eliminate the use of toxic NH3 gas. In addition, utilization of sol-gel-derived Ta2O5 gel as a Ta precursor allowed for completion of nitridation within a shorter period and at a lower calcination temperature compared with the conventional ammonolysis process. Optimization of the reaction conditions, such as the urea content, allowed for the production of solid solutions of SrTaO2N and Sr1.4Ta0.6O2.9. The products exhibited optical absorption and chromatic colors because of the narrower band gaps of oxynitrides compared with those of oxides. The O/N ratios of the solid solutions were easily adjusted by varying the amount of urea in the mixture of precursors. As a result, the colors of the products ranged from yellow to brown. The nitridation process and products developed in this study are interesting environmentally benign alternatives to conventional inorganic pigments., 32220525

Low-Temperature Nitridation of Fe3O4 by Reaction with NaNH2
Sarah E. O'Sullivan, Shi-Kuan Sun, Sebastian M. Lawson, Martin C. Stennett, Feihong Chen, Yuji Masubuchi, Claire L. Corkhill, Neil C. Hyatt
INORGANIC CHEMISTRY, 60, 4, 2553, 2562, AMER CHEMICAL SOC, 2021年02月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Low-temperature soft chemical synthesis routes to transition-metal nitrides are of interest as an alternative to conventional high-temperature ammonolysis reactions involving large volumes of chemotoxic NH3 gas. One such method is the reaction between metal oxides and NaNH2 at ca. 200 degrees C to yield the counterpart nitrides; however, there remains uncertainty regarding the reaction mechanism and product phase assemblage (in particular, noncrystalline components). Here, we extend the chemical tool box and mechanistic understanding of such reactions, demonstrating the nitridation of Fe3O4 by reaction with NaNH2 at 170-190 degrees C, via a pseudomorphic reaction. The more reduced Fe3O4 precursor enabled nitride formation at lower temperatures than the previously reported equivalent reaction with Fe3O4. The product phase assemblage, characterized by X-ray diffraction, thermogravimetric analysis, and Fe-57 Mossbauer spectroscopy, comprised 49-59 mol % epsilon-Fe2+xN, accompanied by 29-39 mol % FeO1-xNx and 8-14 mol % gamma ''-FeN. The oxynitride phase was apparently noncrystalline in the recovered product but could be crystallized by heating at 180 degrees C. Although synthesis of transition-metal nitrides is achieved by reaction of the counterpart oxide with NaNH2, it is evident from this investigation that the product phase assemblage may be complex, which could prove a limitation if the objective is to produce a single-phase product with well-defined electrical, magnetic, or other physical properties for applications. However, the significant yield of the FeO1-xNx oxynitride phase identified in this study opens the possibility for the synthesis of metastable oxynitride phases in high yield, by reaction of a metal oxide substrate with NaNH2, with either careful control of H2O concentration in the system or postsynthetic hydrolysis and crystallization., 32220525

Preparation and thermal stability of oxynitride perovskite solid solution Sr1-xLaxTa1-xTixO2N
Yuji Masubuchi, Sota Ohtaki, Kotaro Fujii, Masatomo Yashima, Mikio Higuchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 40, 16, 6288, 6292, ELSEVIER SCI LTD, 2020年12月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The thermal stability of oxynitride perovskites is very important for the fabrication of their dense ceramics. In this study, a solid solution of the oxynitride perovskite Sr1-xLaxTa1-xTixO2N was prepared via the ammonia nitridation of oxide precursors. The oxynitrides products obtained at x <= 0.2 and x >= 0.7 had tetragonal and triclinic perovskite-type structures, respectively. A neutron diffraction study on the oxynitride product obtained at x = 0.2 indicated that this tetragonal perovskite had a cis-type anion distribution similarly to SrTaO2N. The tetragonal perovskite released a part of nitrogen at approximately 1000 degrees C in a nitrogen atmosphere while maintaining the perovskite structure at least to 1450 degrees C. The oxynitride perovskites at x >= 0.5 gradually decomposed to a mixture of LaTiO2N, LaTiO3, La(OH)(3), La2O3, TiN and TaO above 1100 degrees C., 32220525

Formation and morphological change of BaTaO2N perovskite from BaCN2/Ta2O5 mixture
Akira Hosono, Yuji Masubuchi, Kyohei Koyama, Mikio Higuchi, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 836, 155459, 155459, ELSEVIER SCIENCE SA, 2020年09月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Metal oxynitrides are generally synthesized by heating their component oxides in a flow of ammonia for longer than 20 h. In the present study, pure BaTaO2N oxynitride perovskite powder was obtained by heating a mixture of tetragonal BaCN2 and Ta2O5 in a flow of nitrogen. The BaTaO2N powder synthesized at slightly below the melting point of tetragonal BaCN2 (910 degrees C) was found to consist of coarse aggregates of 300 nm-sized particles based on scanning electron microscopy observations. In contrast, BaTaO2N powder obtained above the melting point of tetragonal BaCN2 contained highly-dispersed particles after washing with acid. This difference is attributed to the dissolution and precipitation of the surfaces of the BaTaO2N grains in the BaCN2 melt to generate grain boundary layers soluble in acid. This work represents the first report of the synthesis of a metal oxynitride using a metal carbodiimide as both the metal and nitrogen source. (C) 2020 Elsevier B.V. All rights reserved., 32220525

Synthesis of perovskite-type oxynitrides SrNb(O,N)(3) and CaTa(O,N)(3) using carbon nitride
Qian Yang, Yuji Masubuchi, Mikio Higuchi
CERAMICS INTERNATIONAL, 46, 9, 13941, 13944, ELSEVIER SCI LTD, 2020年06月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The synthesis of oxynitride perovskites based on the use of gaseous ammonia as the nitrogen source requires high reaction temperatures and long durations. In the resent work, reduction and nitridation reactions using carbon nitride (C3N4) were employed to prepare SrNbO2N and CaTaO2N from their oxide precursors, without the use of ammonia. The phase evolution behaviors and the reaction mechanisms were investigated by acquiring thermogravimetric and X-ray diffraction data. The formation of metal cyanamide as an intermediate was found to be vital to realizing low-temperature synthesis of these compounds. Scanning electron microscopy observations also indicated that the particle sizes of the oxynitrides prepared using C3N4 were smaller than those obtained by ammonolysis reactions, due to the low formation temperature of 800 degrees C associated with the present C3N4 process., 32220525

Spark plasma sintering of dielectric BaTaO2N close to the melting point of the BaCN2 additive
Akira Hosono, Masashi Inoguchi, Yuji Masubuchi, Koji Murayama, Michiaki Iha, Mikio Higuchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 40, 6, 2317, 2322, ELSEVIER SCI LTD, 2020年06月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The perovskite-type oxynitride BaTaO2N is a promising lead-free relaxor ferroelectric material. However, this material releases a part of its nitrogen during its sintering above 1350 degrees C. Subsequent annealing of the resulting sintered BaTaO2N0.85 ceramics under an ammonia flow is necessary to recover an insulating, stoichiometric BaTaO2N ceramics. Very recently, molten BaCN2 was reported to be a useful flux for the preparation of BaTaO2N microcrystals without the loss of nitrogen. In the present work, BaTaO2N powder was sintered with a BaCN2 additive under mechanical pressure, using a spark plasma sintering system. Nitrogen loss from the BaTaO2N ceramic was avoided during liquid phase sintering at approximately 900 degrees C. The stoichiometric BaTaO2N ceramic product with a relative density of 79.8 % was an electrically insulator and it showed its relative dielectric constants, epsilon(r) in the range from 320 to 650 and a loss tans values from 0.04 to 0.19 at room temperature., 32220525

Large red-shift of luminescence from BaCN2:Eu2+ red phosphor under high pressure
Yuji Masubuchi, Sayaka Nishitani, Suzuka Miyazaki, Hansen Hua, Junpei Ueda, Mikio Higuchi, Setsuhisa Tanabe
APPLIED PHYSICS EXPRESS, 13, 4, IOP PUBLISHING LTD, 2020年04月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, We report a new material, BaCN2:Eu2+ for a very sensitive optical pressure sensor, 50 times more sensitive than ruby. Photoluminescence spectra of the BaCN2:Eu2+ phosphor was measured under hydrostatic pressures from ambient pressure to 5.34 GPa at room temperature. The peak wavelength of the luminescence was drastically red-shifted at a rate of 19 nm GPa(-1), which is approximately 50 times larger than that of the ruby, most commonly used as a pressure sensor in the high-pressure experiments. This large shift of the luminescence wavelength is suitable for application in optical pressure sensors for the high-pressure experiments without a high-resolution monochromator., 32220525

ペロブスカイト型酸窒化物強誘電体BaTaO₂N微結晶の作製
細野 新, 鱒渕 友治, 安井 伸太郎, 武貞 正樹, 樋口 幹雄, 伊藤 満, 吉川 信一
応用物理学会学術講演会講演予稿集, 2020.1, 1695, 1695, 公益社団法人 応用物理学会, 2020年02月28日
日本語

Fluorination and reduction of CaCrO3 by topochemical methods
Christian A. Juillerat, Yoshihiro Tsujimoto, Akira Chikamatsu, Yuji Masubuchi, Tetsuya Hasegawa, Kazunari Yamaura
DALTON TRANSACTIONS, 49, 6, 1997, 2003, ROYAL SOC CHEMISTRY, 2020年02月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Topochemical reactions between CaCrO3 and polyvinylidene difluoride yield the new fluorinated phase CaCrO2.5F0.5, which was characterized by powder synchrotron X-ray diffraction, X-ray photoemission spectroscopy, and magnetic susceptibility measurements. The reaction proceeds via reduced oxide intermediates, CaCrO2.67 and CaCrO2.5, in which CrO6 octahedral and CrO4 tetrahedral layers are stacked in a different manner along the c axis of CaCrO3. These two intermediate phases can be selectively synthesized by the carbothermal reduction with g-C3N4. Both CaCrO3 and CaCrO2.5F0.5 adopt the same orthorhombic space group, Pbnm; however, the fluorinated phase has decreased Cr-O-Cr bond angles as compared to the parent compound in both the ab plane and along the c-direction, which indicates an increased orthorhombic distortion due to the fluorination. While the oxygen vacancies are ordered in both intermediate phases, CaCrO2.67 and CaCrO2.5, a site preference for fluorine in the oxyfluoride phase cannot be confirmed. CaCrO3 and CaCrO2.5F0.5 undergo antiferromagnetic phase transitions involving spin canting, where the fluorination causes the transition temperature to increase from 90 K to 110 K, as a result of the competition between the increased octahedral tilting and the enhancement of superexchange interactions involving Cr3+ ions in the CaCrO2.5F0.5 structure., 32220525

窒化炭素を用いた機能性酸窒化物の新規合成手法の開発
鱒渕友治
日本板硝子材料工学助成会成果報告書(Web), 38, 2020年

Ferroelectric BaTaO2N Crystals Grown in a BaCN2 Flux
Akira Hosono, Yuji Masubuchi, Shintaro Yasui, Masaki Takesada, Takashi Endo, Mikio Higuchi, Mitsuru Itoh, Shinichi Kikkawa
INORGANIC CHEMISTRY, 58, 24, 16752, 16760, AMER CHEMICAL SOC, 2019年12月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Perovskite-type oxynitride BaTaO2N has been attracting attention for its large dielectric constant, which is almost independent of the temperature by measurements on its ceramics. Its dielectric characteristics are attributed to polar nanoregions (PNRs) in the average cubic crystal structure. Polarization saturation to produce a butterfly-like piezoresponse force microscopy (PFM) signal was observed on BaTaO2N crystals in the present study. Reddish crystallites of BaTaO2N of up to 3.1 mu m in size were grown using a BaCN2 flux. Grain growth proceeded through the formation of a Ruddlesden-Popper-type oxynitride from the reaction between BaTaO2N powder and molten BaCN2. Their electrical property was studied using PFM with special care because of the small size of the crystals. They were found to be much more highly insulating than its ceramics. Ferroelectricity with complete phase inversion was observed on an oxynitride perovskite crystal for the first time. A large coercivity of 50-60 V was observed in the measurement. Such ferroelectricity is ascribed to the PNRs induced by the polar linkages between cis-type TaO4N2 octahedra., 32220525

Niobium oxynitrides with defective rock salt-type structures
Kota Tateno, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 803, 678, 683, ELSEVIER SCIENCE SA, 2019年09月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The effect of crystal structural defects on superconductivity was investigated in two types of rock salt-type niobium oxynitride structures, (Nb0.87Si0.09 square(0.04)) (N0.87O0.13) and Nb-4(N,O)(5). The first oxynitride had been reported to have an enhanced critical superconducting current J(C) by the doping of Si in the crystal lattice together with some amount of cationic vacancies in our previous publications. In the present study, it was thermally annealed at various high temperature and under nitrogen pressure to study the effect of changing the defect structure on the superconductivity. The doped Si was gradually excluded as SiO2 impurities forming nano crystalline rock salt-type delta-NbN together with NbO2 impurities. The superconducting volume fraction and critical current density decreased following the annealing. The second niobium oxynitride examined, Nb-4(N,O)(5), has a cationic vacancy-ordered rock salt-type crystal structure. Wet ammonolysis led to an improvement of crystallinity in Nb-4.19(N4.50O0.50) in I4/m space group with alpha= 0.6861 (2) nm and c = 0.4284 (1) nm. Magnetic measurements showed that the well-ordered cationic vacancies was especially important to have its superconductivity below 10 K with an increase in superconducting volume fraction to 47.1%. (C) 2019 Elsevier B.V. All rights reserved., 32220525

An electronic structure governed by the displacement of the indium site in In-S-6 octahedra: LnOInS(2) (Ln = La, Ce, and Pr)
Hiroaki Ito, Akira Miura, Yosuke Goto, Yoshikazu Mizuguchi, Chikako Moriyoshi, Yoshihiro Kuroiwa, Masaki Azuma, Jinjia Liu, Xiao-Dong Wen, Shunta Nishioka, Kazuhiko Maeda, Yuji Masubuchi, Nataly Carolina Rosero-Navarro, Kiyoharu Tadanaga
DALTON TRANSACTIONS, 48, 32, 12272, 12278, ROYAL SOC CHEMISTRY, 2019年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, An extremely large displacement of the indium site in In-S-6 octahedra in LnOInS(2) (Ln = La, Ce, and Pr) was found in synchrotron X-ray diffraction. LaOInS2 with off-center indium in In-S-6 octahedra exhibited a wider optical band gap than CeOInS2 and PrOInS2 with on-center indium. Therefore, the electronic structure of LnOInS(2) is governed by the indium site with an extremely large displacement. All LnOInS(2) produced H-2 gas under visible light irradiation in the presence of sacrificial electron donors., 32220525

Melting Behavior of Alkaline-Earth Metal Carbodiimides and Their Thermochemistry from First-Principles
Akira Hosono, Ralf Peter Stoffel, Yuji Masubuchi, Richard Dronskowski, Shinichi Kikkawa
INORGANIC CHEMISTRY, 58, 14, 8938, 8942, AMER CHEMICAL SOC, 2019年07月, ［査読有り］, ［責任著者］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, We present a combined experimental and theoretical investigation targeted at the thermochemical properties of a series of alkaline-earth metal carbodiimides. Their Gibbs energies and decomposition temperatures were calculated on the basis of phonons derived from density functional theory. The theoretical decomposition temperatures arrive at 1270, 1224, and 1185 K for CaNCN, alpha-SrNCN, and tetragonal BaNCN, respectively. Only the melt of tetragonal BaNCN is maintained at similar to 1173 K, which is slightly below its calculated decomposition temperature. Experimentally, the melt of BaNCN did not decompose below 1273 K. On the contrary, both CaNCN and alpha-SrNCN partially decompose by forming a mixture of their carbides, metals, and nitrogen. The calculated Gibbs energies also show that the tetragonal phase of BaNCN is more stable than the rhombohedral one. We conclude that the melt of BaNCN is useful in the crystal growth of oxynitride perovskites such as BaTaO2N., 32220525

Core loss in magnetic rings made of Fe16N2-like iron nitride powder
Yoshiyuki Matsumoto, Yuji Masubuchi, Yoshiyuki Nakazawa, Hitoshi Itami, Masayuki Tsuchiya, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 789, 697, 703, ELSEVIER SCIENCE SA, 2019年06月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The soft magnetic properties of alpha-Fe fine powders were investigated before and after low temperature ammonolysis together with the effect of alumina presence in the grain boundaries to clarify the contribution of these during the preparation process. The crystallite size was controlled to be approximately 50 nm and 30 nm before and after ammonolysis, respectively, by changing the preparation conditions to eliminate the effect of particle size on the magnetic properties. The ammonolysis product was a mixture of approximately 50 wt% of an alpha ''-Fe16N2-like compound (hereafter denoted as "alpha ''-Fe16N2") with residual alpha-Fe, which had the largest magnetization among the ammonolysis products reported in our previous works. The core loss of magnetic rings made from this powder was first studied after sealing in Delrin (R) capsules to avoid decomposition by oxidation and the presence of humidity. The core loss was decreased to one third and the permeability was decreased to approximately 80% by the ammonolysis process, independent of the presence of alumina at the grain boundaries. The hysteresis contribution in the core loss was significantly decreased due to enhanced magnetic domain interaction in the anisotropic crystal lattice of "alpha ''-Fe16N2". The covalent chemical bonds of Fe-N caused the compound to be more electrically resistive and also resulted in a slight decrease of the eddy current loss contribution. Alumina precipitation at the grain boundaries caused a doubling of core loss increase and an increase of the permeability to approximately 130% because the magnetic interaction between grains was reduced by the presence of alumina in the composite products. Combing the decreased core loss by nitridation and the increased magnetic permeability by alumina precipitation will be useful to develop a new soft magnetic material. (C) 2019 Elsevier B.V. All rights reserved., 32220525

Synthesis, crystal structure and properties of a quaternary oxide with a new structure type, BiGaTi4O11
Hisanori Yamane, Ryota Yagi, Akira Hosono, Yuji Masubuchi
ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY, 75, 702, +, INT UNION CRYSTALLOGRAPHY, 2019年06月, ［査読有り］, ［最終著者］, ［国際誌］
英語, 研究論文（学術雑誌）, A new quaternary oxide, BiGaTi4O11 (bismuth gallium tetratitanium undecaoxide), was prepared by heating a mixture of the binary oxides at 1373 K in air. BiGaTi4O11 melts at 1487 K and prismatic single crystals were obtained from a sample melted at 1523 K and solidified by furnace cooling. The structure of BiGaTi4O11 was analyzed using single-crystal X-ray diffraction to be of a new type that crystallized in the space group Cmcm. A Bi3+ site is coordinated by nine O-2 anions, and three oxygen-coordinated octahedral sites are statistically occupied by Ga3+ and Ti 4+ cations. A relative dielectric constant of 46 with a temperature coefficient of 57 ppm K1 in the temperature range 297-448 K was measured for a polycrystalline ceramic sample at 150 Hz-1 MHz with a dielectric loss tan of less than 0.01. Electrical resistivities measured at 1073 K by alternating-current impedance spectroscopic and direct-current methods were 1.16 10 4 and 1.14 10 4 S cm 1, respectively, which indicates that electrons and/or holes were conduction carriers at high temperature. The optical band gap estimated by the results of diffuse reflectance analysis was 2.9-3.0 eV, while the band gap obtained from the activation energy for electrical conduction was 3.5 eV.

Stepwise topochemical fluorination of SrCrO3 perovskite via a super-structured oxide
Yu Su, Yoshihiro Tsujimoto, Kotaro Fujii, Yuji Masubuchi, Hirohito Ohata, Hideo Iwai, Masatomo Yashima, Kazunari Yamaura
CHEMICAL COMMUNICATIONS, 55, 50, 7239, 7242, ROYAL SOC CHEMISTRY, 2019年06月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, A topochemical reaction between SrCrO3 and polyvinylydene fluoride yields the new fluorinated phase SrCrO2.8F0.2. The transformation proceeds via a reduced oxide intermediate (SrCrO2.8) that can be isolated as a single phase by the reaction between SrCrO3 and g-C3N4. The fluoride ions randomly occupy anion sites despite an oxygen-vacancy ordered structure in SrCrO2.8., 32220525

Utility of ZnGa2O4 Nanoparticles Obtained Hydrothermally for Preparation of GaN:ZnO Solid Solution Nanoparticles and Transparent Films
Yusuke Asakura, Yukiho Nishimura, Yuji Masubuchi, Shu Yin
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, 14, 1999, 2005, WILEY-V C H VERLAG GMBH, 2019年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, GaN:ZnO solid solution nanoparticles and films were synthesized by using ZnGa2O4 nanoparticles with a particle size of below 25 nm obtained hydrothermally as a precursor. Nitridation of powder ZnGa2O4 nanoparticles led to the formation of GaN:ZnO nanoparticles. The nitrided samples have higher specific surface area than those obtained by conventional method, which induces higher photocatalytic NOx decomposition activity. In addition, a transparent coating film with ZnGa2O4 nanoparticles was converted to GaN:ZnO film after nitridation. The nitrided film absorbs UV and blue light and is transparent for light of wavelength over 500 nm (the transmittance is over 90 %). This means that the nitridation does not lead to the formation of scattering domains by the large-size particles and cracks. This method for film preparation is much cheaper than conventional CVD and sputtering processes. These results strongly suggest the utility of ZnGa2O4 nanoparticles not only for the formation of GaN:ZnO solid solution nanoparticles with high specific surface area but also for the preparation of transparent GaN:ZnO solid solution films., 32220525

Preparation of LaTiO2N Using Hydrothermally Synthesized La2Ti2O7 as a Precursor and Urea as a Nitriding Agent
Ryoki Okada, Kiyofumi Katagiri, Yuji Masubuchi, Kei Inumaru
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, 9, 1257, 1264, WILEY-V C H VERLAG GMBH, 2019年03月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, A facile method was successfully developed to prepare perovskite-type metal oxynitrides, LaTiO2N, from La2Ti2O7 as a precursor in an atmosphere of N-2. Urea was employed as a solid-state nitriding agent, instead of gaseous NH3, to increase the safety of the reaction. The hydrothermally prepared La2Ti2O7 precursor had a nanosheet morphology and contained La(OH)(3) as a by-product. Through the optimization of reaction conditions including heat-treatment temperature and content of urea, single-phase LaTiO2N could be obtained. In addition, we revealed that the La(OH)(3) present in the La2Ti2O7 precursor played an important role in the nitriding process using urea. La2O2CN2 was generated by the reaction of La(OH)(3) with the thermal decomposition products of urea at the medium temperature range. This indicated that the NH3 gas released from the thermal decomposition of urea did not directly cause nitridation of the La2Ti2O7 precursor., 32220525

酸窒化物誘電体の新合成法
鱒渕友治
応用物理, 88, 5, 2019年

Colored amorphous silica-based powder with TiN nanocrystals precipitated by ammonolysis of Ti-Si-O ternary glass
Yuki Sagawa, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 102, 1, 109, 117, WILEY, 2019年01月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Coloration of amorphous silica powder containing titania was investigated by nitridation in an ammonia flow. The oxide precursors were obtained by the hydrolysis of a mixture of tetraethyl orthosilicate (TEOS) and tetrabutoxy titanium (TBT). The color changed with the amount of TBT in the mixture, the hydrolysis pH and the ammonolysis temperature. The original white color of the 8 mol% TBT powder hydrolyzed under basic pH conditions changed to pale goldenrod at 700 degrees C, then to dark olive green at 800 degrees C, and further darkened with increasing ammonolysis temperature. A steel-blue color appeared at 900 degrees C for the powder obtained with 3 mol% TBT, and increased in darkness at 1000 degrees C. A similar bluish color was observed for powders obtained by acidic hydrolysis after ammonolysis above 900 degrees C, and this was independent of the amount of titania, although the chroma decreased with increasing firing temperature for the powder with 3 mol% TBT. The ammonolysis powder products were characterized using X-ray diffraction (XRD), electron probe micro analysis (EPMA), transmission electron microscopy-electron energy-loss spectroscopy (TEM-EELS), scanning transmission electron microscopy-high-angle annular dark-field imaging (STEM-HAADF) and Ti-K edge X-ray absorption fine structure (XAFS). The color change was related to both precipitated TiN nanocrystals and residual titanium in the amorphous silica matrix. The TiN exhibited a goldish reflection and also plasmonic absorption from light blue to gray depending on the TiN crystallite size. The plasmonic absorption and resonance of nanocrystalline TiN will be useful similarly to that of gold in nanotechnology for various kinds of energy application.

Precipitation of metal nitride nanoparticles from amorphous (M,Si)-(N,O) thin films (M=Nb, Zr)
Yuji Masubuchi, Yuko Miyamoto, Shinichi Kikkawa
MATERIALS TODAY-PROCEEDINGS, 16, 173, 179, ELSEVIER, 2019年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（国際会議プロシーディングス）, Crystallization of metal nitride nanoparticles from amorphous matrix upon thermal annealing was investigated by studying the plasmonic absorption behavior of the nanoparticles. Amorphous silicon oxynitride thin films containing various amounts of M (M = Zr, Nb) were deposited by RF magnetron sputtering from a M/Si composite target using nitrogen as a reactive sputtering gas. The optical transmittance at around 700 nm of the annealed thin film decreased due to plasmonic absorption by the metallic NbN nanoparticles. The nanoparticles precipitated homogeneously in the Si(N,O) matrix upon annealing the Nb1-xSix(N, O) thin film with x = 0.7 at 700 degrees C. In contrast, for Zr1-ySiy(N,O) thin films with y = 0.4 and 0.5, ZrN nanoparticles did not precipitate even after thermal annealing due to the stability of zirconium oxide in the Si(N, O) matrix, resulting in no significant change in the interference color of the thin films. (C) 2019 Elsevier Ltd. All rights reserved., 32220525

Magnetic core/shell-type composites composed of coarse FePt particles coated with finely powdered iron nitride
Ryoji Yamauchi, Yuji Masubuchi, Shinichi Kikkawa
MATERIALS RESEARCH BULLETIN, 106, 124, 130, PERGAMON-ELSEVIER SCIENCE LTD, 2018年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Although alpha ''-Fe16N2-like compounds exhibit enhanced magnetization compared to alpha-Fe, it is important to increase their magnetic coercivity to obtain new hard magnetic materials for electric vehicle application. In the present work, coarse FePt particles were coated with finely powdered Fe3O4 produced by the hydrolysis of Fe (acac)(3) in benzyl alcohol. This Fe3O4 coating layer was subsequently reduced under hydrogen and then nitrided by ammonolysis at 150 degrees C to obtain a dual-phase mixture of an alpha ''-Fe16N2-like compound (referred to herein as "alpha ''-Fe16N2") and residual alpha-Fe. The ("alpha ''-Fe16N2" + alpha-Fe)(1-x)/(FePt)(x) composite particles for which x = 0.2, 0.4 or 0.6 generated smooth magnetization hysteresis curves, and the magnetic coercivity of these materials increased with increases in the proportion of FePt. Magnetic coupling was clearly evident between the core and shell regions in the composite powder for which x = 0.6, as demonstrated by a plot of the Wohlfarth interaction against the magnetic field. Transmission electron microscopy images confirmed magnetic coupling between the coarse FePt particles (several hundred nm in diameter) and the coating of fine mixed particles (several tens of nm in diameter) of "alpha ''-Fe16N2" and alpha-Fe. The "alpha ''-Fe16N2" crystals forming the particle shell were found to grow epitaxially, aligning their c-axes parallel to that of the tetragonal FePt.

Remarkable effects of local structure in tantalum and niobium oxynitrides
Shinichi Kikkawa, Akira Hosono, Yuji Masubuchi
PROGRESS IN SOLID STATE CHEMISTRY, 51, 71, 80, PERGAMON-ELSEVIER SCIENCE LTD, 2018年09月, ［査読有り］, ［最終著者］, ［国際誌］
英語, Compounds that contain two types of anion are attracting attention as a new field of solid state chemistry. The nitride anion is similar to the oxide anion in size and nature. They coordinate together to cations in oxynitrides to form characteristic local structures around them in a certain way. Special properties induced by the specific local structure have been observed in oxynitrides. Ferroelectricity was identified in oxynitride perovskites, especially those of tantalum, because the oxide and nitride anions form a polar ordered local crystal structure around Ta5+ in the 5d(0) electron configuration. The critical current density in superconductivity was enhanced by the formation of clusters in niobium oxynitrides with the rocksalt-type structure. Main group elements doped into the niobium oxynitrides, especially silicon, are coordinated mainly by oxides with some amount of nitrides to form silicon oxide-like clusters. The niobium in the oxynitride has some 4d electrons to maintain the superconductivity in the niobium oxynitride host. Here, the preparation, crystal structure and properties of oxynitrides formed with tantalum and niobium are reviewed. (C) 2017 Elsevier Ltd. All rights reserved.

Magnetic iron nitrides inspired by historic research on α″-Fe16N2
Shinichi Kikkawa, Yuji Masubuchi
Progress in Solid State Chemistry, 51, 19, 26, PERGAMON-ELSEVIER SCIENCE LTD, 2018年09月, ［査読有り］, ［最終著者］, ［国際誌］
英語, © 2017 Elsevier Ltd. Strong ferromagnetic materials at room temperature are of interest for various magnetic applications such as magnetic recording, sensors, and motors. Gigantic magnetism expected for α″-Fe 16 N 2 thin films had been attracted much attention in terms of its large magnetization per weight in comparison to rare earth iron nitrides R 2 Fe 17 N 3 because these films are made of only iron and nitrogen. It developed much straggling on iron nitride thin film research but inconsistent results were obtained using different preparation methods. A powdered α″-Fe 16 N 2 -like compound was prepared by the ammonolysis of fine α-Fe powder in low temperature below 200 °C to clarify the confusion; the magnetism was not large in α″-Fe 16 N 2 itself but was increased in the intermediate ammonolysis dual-phase mixture product of the α″-Fe 16 N 2 -like compound and residual α-Fe. A way to control the magnetic coercivity was subsequently investigated to utilize the larger magnetization in the α″-Fe 16 N 2 -like compound mixture as magnetic materials similarly to Sm 2 Fe 17 N 3 bonded magnet. Iron nitrides, zinc blende type γ″-FeN and rock-salt type γ‴-FeN, also decompose at around 500 °C. Thermal decomposition was a disadvantage in the preparation of the iron nitrides; however, iron nanoparticles dispersed composites in AlN matrix were derived from the iron nitrides (Fe,Al)N by thermal treatment including laser heating. Iron nitrides are thus promising magnetic materials for their potential applications in science and technology.

Intergrowth between the Oxynitride Perovskite SrTaO2N and the Ruddlesden-Popper Phase Sr2TaO3N
Yuya Suemoto, Yuji Masubuchi, Yuki Nagamine, Atsuo Matsutani, Takeshi Shibahara, Kumiko Yamazaki, Shinichi Kikkawa
INORGANIC CHEMISTRY, 57, 15, 9086, 9095, AMER CHEMICAL SOC, 2018年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Strontium tantalum oxynitrides were prepared within the nominal composition range of 1.0 <= x <= 2.0, where x = Sr/Ta atomic ratio. A gradual structural transition was observed between the perovskite SrTaO2N and the Ruddlesden-opper phase Sr2TaO3N with increasing SrO content. X-ray diffraction analyses showed that a single-phase perovskite was obtained up to x = 1.1, after which Sr2TaO3N gradually appeared at x >= 1.25. High-resolution scanning transmission electron microscopy observations identified the gradual intergrowth of a Ruddlesden-Popper Sr2TaO3N type planar structure interwoven with the perovskite crystal lattice upon increasing x. The crystal lattice at x = 1.4 was highly defective and consisted primarily of perovskite intergrown with a large amount of the Ruddlesden-Popper phase structure. This Ruddlesden-Popper phase layer intergrowth is a characteristic of an oxynitride perovskite rather than the Ruddlesden-Popper defects previously reported in oxide perovskites. Partial substitution of Ta with Sr was also evident in this perovskite lattice. Just below x = 2, a perovskite-type structure was intergrown as defects in the Ruddlesden-Popper Sr2TaO3N. Characterization of Sr2TaO3N in ambient air was challenging due to its moisture sensitivity. Thermal analysis demonstrated that this material was relatively stable up to approximately 1400 degrees C in comparison with SrTaO2N perovskite, especially under nitrogen. Sr2TaO3N could keep its structure in a sealed tube, and some amount of SrCO3 was observed in XRD after 10 days of exposure to 75% relative humidity under prior ambient conditions. A compact of this material had a relative density of 96% after sintering at 1400 degrees C under 0.2 MPa of nitrogen, even though a drastic loss of nitrogen was previously reported for a SrTaO2N perovskite under these same conditions. Postammonolysis of the Sr2TaO3N ceramics was not required prior to studying its dielectric behavior. This is in contrast to the SrTaO2N perovskite, which requires postammonolysis to recover its stoichiometric composition and electrical insulating properties., 32220525

Piezoresponse and microstructure of BaTaO2N ceramics
Akira Hosono, Yuji Masubuchi, Yuki Nagamine, Takeshi Shibahara, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 38, 10, 3478, 3482, ELSEVIER SCI LTD, 2018年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Piezoresponse force microscopy was conducted on a polished slice of the perovskite oxynitride ceramic BaTaO2N after ammonolysis at a bias voltage of +/- 10 V. The ceramic surface was relatively porous because it was readily hydrolyzed by ambient humidity. While there was no piezoresponse on the surface of the ultrathin slice, a piezoresponse was clearly observed just below the surface of a thick slice. The response was enhanced in a denser sample. It increased with measuring voltage up to 7 V, and then gradually decreased up to 9 V. The response also gradually decreased with time but persisted even after 150 min at a measuring voltage of 6 V. Microstructural characterization revealed well-sintered grains, about 100 nm in size, in a relatively dense BaTaO2N structure. High-porosity BaTaO2N did not show any piezoresponse because its porous surface was easily hydrolyzed. A weak piezoresponse was observed for an electrically conductive slice obtained from deep inside a relatively dense BaTaO2N ceramic after ammonolysis., 32220525

Direct synthesis of nearly single phase SrTaO2N from SrCO3/TaN
Shan-Lu Chen, Wei-Ming Guo, Shi-Kuan Sun, Yuji Masubuchi, Ming Lv, Hua-Tay Lin, Cheng-Yong Wang
CERAMICS INTERNATIONAL, 44, 4, 4504, 4507, ELSEVIER SCI LTD, 2018年03月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, In this work, nearly single phase SrTaO2N powder was directly prepared from strontium carbonate (SrCO3) and tantalum mononitride (TaN), instead of the nitridation of the oxide precursors using NH3. The phase evolution and reaction mechanism together with the chemical composition, crystal structure and particle size of SrTaO2N product were investigated. Similar to the reactions between SrCO3 and Ta3N5, the evolution of CO3, CO and N-2 was detected during the reactions. The results revealed that this novel reaction was able to successfully synthesize orange-coloured SrTaO2N powder with nearly pure phase at 1200 degrees C and the powder possessed the uniform size distribution with the mean diameter of 6.63 mu m., 32220525

Synthesis of graphitic carbon nitride from different precursors by fractional thermal polymerization method and their visible light induced photocatalytic activities
Zhihuan Zhao, Yan Ma, Jimin Fan, Yongqiang Xue, Honghong Chang, Yuji Masubuchi, Shu Yin
JOURNAL OF ALLOYS AND COMPOUNDS, 735, 1297, 1305, ELSEVIER SCIENCE SA, 2018年02月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Graphitic carbon nitride(g-C3N4) polymer was successfully synthesized by a fractional thermal polymerization method using melamine, guanidine carbonate and dicyandiamide as precursors. The detailed characterization was carried out by TG-DTG, XRD, SEM, PL, DRS, XPS and BET. The photocatalytic performance was determined by degradation of methyl orange(MO) under visible light irradiation. g-C3N4 obtained from different raw materials and temperature showed different band gap, morphology and photocatalytic activities. The g-C3N4 could be obtained by the polymerization reaction of melamine, guanidine carbonate or dicyandiamide at 515, 550 or 515 degrees C, respectively. The treatment temperature affected the final properties of the g-C3N4 particles. The g-C3N4-M(melamine, 600 degrees C), g-C3N4D(dicyandiamide, 590 degrees C) and g-C3N4-G (guanidine carbonate, 550 degrees C) particles showed the best MO degradation photocatalytic performances under visible light irradiation (> 400 nm) for 120min. (C) 2017 Elsevier B.V. All rights reserved., 32220525

Red-emission over a wide range of wavelengths at various temperatures from tetragonal BaCN2:Eu²⁺
Yuji Masubuchi, Sayaka Nishitani, Akira Hosono, Yuuki Kitagawa, Jumpei Ueda, Setsuhisa Tanabe, Hisanori Yamane, Mikio Higuchi, Shinichi Kikkawa
Journal of Materials Chemistry C, 6, 24, 6370, 6377, ROYAL SOC CHEMISTRY, 2018年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, © 2018 The Royal Society of Chemistry. A new polymorph of BaCN2 was obtained via a simple nitridation reaction of BaCO3 under an NH3 flow at 900 °C. The product was analyzed via single crystal X-ray diffraction and infrared spectroscopy, and it was found to have a tetragonal I4/mcm crystal structure (space group no. 140) with a = 0.60249(4) nm and c = 0.71924(5) nm. In this structure, each Ba2+ cation is situated in the square antiprism of N atoms of NCN2- anionic groups. Eu2+ doped BaCN2 can be excited by irradiation of blue and green light (from 400 to 550 nm), and it generates an intense red emission peak at 660 nm with a quantum efficiency of 42% in response to 465 nm excitation at room temperature. The peak emission wavelength varies over an extremely wide range of temperature, from 640 nm at 500 K to 680 nm at 80 K, and this red-shift with decreasing temperature is attributed to a unit cell shrinkage that results in significant crystal field splitting of the 5d energy levels of the Eu2+ ions., 32220525

Synthesis of gallium oxynitride nanoparticles through hydrothermal reaction in the presence of acetylene black and their photocatalytic NOx decomposition
Yusuke Asakura, Yoshiyuki Inaguma, Koichiro Ueda, Yuji Masubuchi, Shu Yin
NANOSCALE, 10, 4, 1837, 1844, ROYAL SOC CHEMISTRY, 2018年01月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Gallium oxynitride (GaON) nanoparticles were synthesized through three steps; (i) hydrothermal treatment of an aqueous solution containing Ga(NO3)(3), hexamethylenetetramine (HMT), and acetylene black, (ii) calcination, and (iii) nitridation. The presence of acetylene black in the hydrothermal treatment is effective for the synthesis of Ga2O3 nanoparticles after the calcination. The intermediate obtained after the hydrothermal reaction possessed no detectable Ga particles in the TEM observation, although the presence of Ga was confirmed in the EDS measurement. This means that acetylene black (AB), in this study, cannot play a simple role as a template. The GaON nanoparticles obtained from the Ga2O3 nanoparticles through nitridation possessed a higher oxygen content than that from Ga2O3 obtained by hydrothermal synthesis without acetylene black and the subsequent calcination. The obtained GaON nanoparticles show higher photocatalytic NOx decomposition activity than bulk GaON synthesized under the same conditions except without acetylene black in the hydrothermal reaction, because of the longer absorption edge and the higher specific surface area. In addition, the effect of nitridation temperature and time on the obtained GaON nanoparticles and their photocatalytic activity was also investigated. Consequently, nanoparticle morphology of a precursor for GaON is important not only for high surface area but also for high visible-light response., 32220525

Synthesis of the Perovskite SrTaO2N Using C3N4 for Both Reduction and Nitridation
Yuji Masubuchi, Mikiya Tadaki, Shinichi Kikkawa
CHEMISTRY LETTERS, 47, 1, 31, 33, CHEMICAL SOC JAPAN, 2018年01月, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
英語, 研究論文（学術雑誌）, The perovskite-type oxynitride SrTaO2N was synthesized from Sr2Ta2O7 and carbon nitride (C3N4) and the formation mechanism was investigated using X-ray diffraction and thermogravimetry combined with mass spectrometry. In this process, ammonia is not required for the nitridation of the oxide. The C3N4 thermally decomposes to gaseous C2N2, which forms SrCN2 and Ta3N5 intermediates on the Sr2Ta2O7. These intermediates then react with the oxide to form SrTaO2N at 800 degrees C, which is 200 degrees C lower than the temperature required for the ammonolysis of Sr2Ta2O7. The product was SrTaO2N, having a slight nitrogen deficiency and small particle size because the present C3N4 nitridation was performed at lower temperature than conventional ammonolysis., 32220525

Magnetic properties of alpha ''-Fe16N2-like compound derived from Fe3O4 fine powder coated on hard magnetic BaFe12O19 particles
Yuta Tsugawa, Yoshiyuki Matsumoto, Yuji Masubuchi, Tetsuo Uchikoshi, Shinichi Kikkawa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 443, 73, 78, ELSEVIER SCIENCE BV, 2017年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, An increase in magnetic coercivity is important for the alpha ''-Fe16N2-like compound with an enhanced magnetization from alpha-Fe as a new hard magnetic material. In the present study, BaFe12O19 particles were coated with fine Fe3O4 powder produced by hydrolysis of Fe(acac)(3) in benzyl alcohol. Smooth magnetization curves were obtained for the composite particles, suggesting they were magnetic hybrids with strong magnetic coupling between the Fe3O4 coating and the BaFe12O19 core particles. The Fe3O4 coating layer was then nitrided by ammonolysis at 150 degrees C to produce a dual-phase mixture of an alpha ''-Fe16N2-like compound, which we refer to as "alpha ''-Fe16N2", and residual alpha-Fe. Smooth magnetization hysteresis curves were obtained for ("alpha ''-Fe16N2")(0.31)(alpha-Fe)(0.69)/BaFe12O19 particles, and a magnetic coercivity of 199 mT, compared to the value of just 65 mT for ("alpha ''-Fe16N2")(0.57)(alpha-Fe)(0.43) powder, indicating magnetic coupling between the core and shell structures. Thus, the hybrid particles exhibited both high magnetization and coercivity. (C) 2017 Elsevier B. V. All rights reserved.

Molten BaCN2 for the sintering and crystal growth of dielectric oxynitride perovskites Sr1-xBaxTaO2N (x=0.04-0.23)
Akira Hosono, Yuji Masubuchi, Takashi Endo, Shinichi Kikkawa
DALTON TRANSACTIONS, 46, 48, 16837, 16844, ROYAL SOC CHEMISTRY, 2017年12月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Solid phase sintering of dielectric oxynitride perovskites above 1000 degrees C is accompanied by their decomposition. Post-ammonolysis is required to recover their stoichiometric nitrogen content and dielectric properties. In the present work, the oxynitride perovskite SrTaO2N was sintered with a BaCN2 flux at approximately 900 degrees C avoiding its thermal decomposition. The resulting solid product with a relative density of 68.9% showed relative dielectric constants in the range from 68 to 90 with loss values less than 0.11, without the post-ammonolysis. The interior of the solids contained rectangular Sr1-xBaxTaO2N crystals for which 0.04 <= x <= 0.23 reflecting their euhedral form. These crystals were grown in molten BaCN2 from 20 to 100 times larger than the original SrTaO2N particles and had a maximum grain size of 3.7 mu m. The Sr1-xBaxTaO2N precipitated on the surfaces of the residual SrTaO2N crystals that had partially dissolved in the BaCN2 flux. A compositional gradient from barium-rich to strontium-rich was observed in a single crystal of the product on going from the exterior to the interior. This is the first-ever report of the preliminary liquid phase sintering and crystal growth of a dielectric oxynitride perovskite using a molten metal cyanamide., 32220525

Magnetic porous iron oxide monoliths prepared through epoxide-mediated sol-gel process
Daichi Jinmori, Yuji Masubuchi, Shinichi Kikkawa
MATERIALS RESEARCH BULLETIN, 88, 214, 217, PERGAMON-ELSEVIER SCIENCE LTD, 2017年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Magnetic porous iron oxide monoliths were obtained using a polyethylene oxide-mediated sol-gel process. The hietarchical porous structure in the xerogel monolith of FeO(C3H7O3)(0.69)(OH)(031).0.42(HCI). 1.08(polyacrylamide) was preserved with pore diameters of 1-4 mu m in the oxide monoliths after calcinations in air at 350 degrees C for various duration. The iron oxide monolith exhibited ferromagnetic behavior in magnetization vs. magnetic field curve after firing at 350 degrees C for 6 h. Both magnetization and magnetic coercivity can be optimized by changing the calcinations condition to obtain the iron oxide monoliths. The fetromagnetic iron oxide monolith will be much more useful in continuous separation than magnetic particles in a wide range of separation especially in biotechnology industry. (C) 2016 Elsevier Ltd. All rights reserved.

Preparation and optical property of gallium zinc oxynitride powder and nanocrystals with sawtooth-like appearance
Atsuo Kamura, Yuji Masubuchi, Teruki Motohashi, Shinichi Kikkawa
MATERIALS RESEARCH BULLETIN, 87, 130, 134, PERGAMON-ELSEVIER SCIENCE LTD, 2017年03月, ［査読有り］, ［責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Gallium zinc oxynitride powder and its nanocrystals were obtained by nitridation of a ZnGa2O4 precursor under NH3 flow. The nitrided powder had the chemical composition of (Ga0.75Zn0.23 square(0.02)) (N0.71O0.29), where square indicates a vacancy, and showed improved crystallinity with a decrease in cationic vacancies compared to that for pristine gallium oxynitride without zinc. Gallium zinc oxynitride nanocrystals with rod-like morphology were obtained by nitridation of the oxide precursor on a NiO pellet. The nanorod crystals were several hundred nanometers wide and several micrometers long. The nanorods had a sawtooth appearance with triangular grains aligned along the length direction of the rods. The nanocrystals with a chemical composition of Ga/Zn = 0.80/0.20 exhibited a broad cathodoluminescence emission at 2.1 eV, similar to the powder products. (C) 2016 Elsevier Ltd. All rights reserved.

Sintering behavior of dielectric SrTaO2N under high pressure of nitrogen
Akira Hosono, Yuji Masubuchi, Shinichi Kikkawa
CERAMICS INTERNATIONAL, 43, 2, 2737, 2742, ELSEVIER SCI LTD, 2017年02月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The sintering behavior of SrTaO2N under high pressure of nitrogen was studied using hot isostatic pressing equipment as a furnace. Some nitrogen was lost during high-temperature sintering to SrTaO2N0.7 even under 190 MPa of N-2, changing the sample color from orange to dark brown or black as in the previous study with 0.2 MPa N-2. The relative density (RD) was less than 90% and voids were observed in the sintered bulks. SrCO3 additive depressed the further decomposition of SrTaO2N0.7 and densification. Grain growth was much enhanced in the sintering at above 1500 degrees C with the decomposition leaving closed pores in the ceramics in case of the sintering without SrCO3 additive. Post-ammonolysis effectively compensated for the partial loss of nitrogen from SrTaO2N ceramics sintered below 1450 degrees C with RD < 80% and recovered the insulating behavior with relative dielectric constants epsilon(r) of 70-120 and tans < 0.1. Their frequency dependence was also studied.

Additive sintering and post-ammonolysis of dielectric BaTaO2N oxynitride perovskite
Akira Hosono, Shi-Kuan Sun, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 36, 14, 3341, 3345, ELSEVIER SCI LTD, 2016年11月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The sintering and thermal stability of BaTaO2N oxynitride perovskite were investigated as an alternative to SrTaO2N dielectric ceramics. The decomposition behaviors of the perovskites were similar, and the temperatures were slightly lower for BaTaO2N than for SrTaO2N. A BaTaO2N compact containing 2.5 wt% BaCO3 sintering aid was sintered at 1400 degrees C in 0.2 MPa N-2. Post-ammonolysis was necessary for the sintered black ceramics to recover the original red color. The insulating post-ammonolysis product with a relative density RD = 73.0% showed a real relative permittivity epsilon(r) = 620 and a tan delta = 0.4 at 10(2) Hz, which changed slightly to epsilon(r) = 320 with tan delta = 2.0 x 10(-2) at 10(8) Hz. The porosity was necessary to eliminate the electronic contribution affected on the extremely large values reported by Kim et al. in 2004 [1]. BaTaO2N ceramics showed better dielectric performance than SrTaO2N ceramics and it changed a little at temperatures up to 150 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.

Nitrogen-Rich Manganese Oxynitrides with Enhanced Catalytic Activity in the Oxygen Reduction Reaction
Akira Miura, Carolina Rosero-Navarro, Yuji Masubuchi, Mikio Higuchi, Shinichi Kikkawa, Kiyoharu Tadanaga
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 55, 28, 7963, 7967, WILEY-V C H VERLAG GMBH, 2016年07月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The catalytic activity of manganese oxynitrides in the oxygen reduction reaction (ORR) was investigated in alkaline solutions to clarify the effect of the incorporated nitrogen atoms on the ORR activity. These oxynitrides, with rock-saltlike structures with different nitrogen contents, were synthesized by reacting MnO, Mn2O3, or MnO2 with molten NaNH2 at 240-280 degrees C. The anion contents and the Mn valence states were determined by combustion analysis, powder X-ray diffraction, and X-ray absorption near-edge structure analysis. An increase in the nitrogen content of rock-salt-based manganese oxynitrides increases the valence of the manganese ions and reinforces the catalytic activity for the ORR in 1m KOH solution. Nearly single-electron occupancy of the antibonding e(g) states and highly covalent Mn-N bonding thus enhance the ORR activity of nitrogen-rich manganese oxynitrides.

Significant Lanthanoid Substitution Effect on the Redox Reactivity of the Oxygen-Storage Material BaYMn2O5+delta
Teruki Motohashi, Makoto Kimura, Yuji Masubuchi, Shinichi Kikkawa, Janine George, Richard Dronskowski
CHEMISTRY OF MATERIALS, 28, 12, 4409, 4414, AMER CHEMICAL SOC, 2016年06月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, The redox characteristics of oxygen storage materials BaLnMn(2)O(5+delta), with Ln = La, Nd, Gd, and Y, were investigated employing the reductive water dissolution by the deoxygenated delta = 0 form. The Ln = La, Nd, and Gd compounds were found to show a capability to produce hydrogen gas through the water dissolution at 500 degrees C, whereas the Ln = Y compound was unreactive to water. It was also revealed that the reactivity obviously depends upon the Ln species: the larger the ionic size of Ln(3+), the higher reactivity the BaLnMn(2)O(5.0) samples exhibit. The experimentally derived thermodynamic parameters of the BaLnMn(2)O(5+delta) series were compared to those obtained by first-principles calculations.

Crystal structure study of dielectric oxynitride perovskites La1-xSrxTiO2+xN1-x (x=0, 0.2)
Daiki Habu, Yuji Masubuchi, Shuki Torii, Takashi Kamiyama, Shinichi Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 237, 254, 257, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2016年05月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, As is the case with SrTaO2N, both cis-ordering of nitride anions and octahedral titling are also preferable in La1-xSrxTiO2+xN1-x (x=0, 0.2) oxynitride perovskites. A larger dielectric constant of epsilon(r) approximate to 5.0 x 10(3) was estimated for the pure oxynitride with x=0.2, compared with epsilon(r) approximate to 1750 for the product with x=0, by extrapolating the epsilon(r) values obtained from powders mixed with paraffin at various mixing ratios. The crystal structure of x=0.2 with larger tolerance factor than x=0 increased the octahedral tilting, which contributes to the increased dielectric constant. The increased dielectric constant supports the exchange mechanism for the dielectric property between two kinds of -Ti-N- helical coils (clockwise and anticlockwise) derived from the above cis -ordering of nitride anions. (C) 2016 Elsevier Inc. All rights reserved.

Partial nitrogen loss in SrTaO2N and LaTiO2N oxynitride perovskites
Daixi Chen, Daiki Habu, Yuji Masubuchi, Shuki Torii, Takashi Kamiyama, Shinichi Kikkawa
SOLID STATE SCIENCES, 54, 2, 6, ELSEVIER SCIENCE BV, 2016年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, SrTaO2N heated in a helium atmosphere began to release nitrogen of approximately 30 at% at 950 degrees C while maintaining the perovskite structure and its color changed from orange to dark green. Then it decomposed above 1200 degrees C to a black mixture of Sr1.4Ta0.6O2.73, Ta2N, and Sr5Ta4O15. The second decomposition was not clearly observed when SrTaO2N was heated in a nitrogen atmosphere below 1550 degrees C. After heating at 1500 degrees C for 3 h under a 0.2 MPa nitrogen atmosphere, the perovskite product became dark green and conductive. Structure refinement results suggested that the product was a mixture of tetragonal and cubic perovskites with a decreased ordering of N3-/O2-. The sintered body was changed to an n-type semiconductor after a partial loss of nitrogen to be reduced from the originally insulating SrTaO2N perovskite lattice. LaTiO2N was confirmed to have a similar cis-configuration of the TiO4N2 octahedron as that of TaO4N2 in SrTaO2N. It also released some of its nitrogen at 800 degrees C changing its color from brown to black and then decomposed to a mixture of LaTiO3, La2O3, and TiN at 1100 degrees C. These temperatures are lower than those in SrTaO2N. (C) 2015 Elsevier Masson SAS. All rights reserved.

Ferroelectric Response Induced in cis-Type Anion Ordered SrTaO2N Oxynitride Perovskite
Shinichi Kikkawa, Shikuan Sun, Yuji Masubuchi, Yuki Nagamine, Takeshi Shibahara
CHEMISTRY OF MATERIALS, 28, 5, 1312, 1317, AMER CHEMICAL SOC, 2016年03月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Oxynitride perovskite SrTaO2N has been attracting attention as a possible new dielectric material owing to the cis-type anion ordering in its crystal structure. It is currently difficult to obtain it in bulk form because it easily loses a part of its nitrogen to become semiconducting during densification at high temperature. We found that its surface layer recovered its original orange color and dielectric properties after postannealing in ammonia. Piezoresponse force microscopy measurements clearly revealed a ferroelectric behavior on the entire orange surface layer peeled off from the black sintered body inside. The present sample was freestanding at about 8 mu m thick and clearly distinct from the compressively strained SrTaO2N thin films for which ferroelectricity was recently reported in small domains (10-10(2) nm) in the locally assumed trans-type anion ordering. The present results represent the first experimental observation of ferroelectric response in a bulk oxynitride perovskite with cis-type anion ordering.

ペロブスカイト型酸窒化物の局所的秩序構造と誘電特性 (特集 誘電体結晶の新展開 : 来たるべきIoT社会へ向けて)
鱒渕 友治, 吉川 信一
日本結晶成長学会誌 Journal of the Japanese Association for Crystal Growth, 43, 3, 176, 182, 日本結晶成長学会, 2016年, ［筆頭著者, 責任著者］, ［国内誌］
日本語, <p>  Perovskite-type oxynitride, having oxide and nitride ions together in a compound, is a new class of dielectric material. Its dielectric property is related to the anionic configuration of short-range cis-type O/N ordering in crystal structure. Dielectric property including piezoelectric response was found out on its dense sintered ceramics. In this report, our recent studies on perovskite-type oxynitride dielectrics are reviewed with a characterization of crystal structure, development of sintering process and observation of a ferroelectric response in an oxynitride bulk ceramics.</p>

Effects of manganese and nickel addition on the preparation of niobium oxynitrides
Y. Kitahara, Y. Masubuchi, T. Motohashi, S. Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 35, 12, 3349, 3353, ELSEVIER SCI LTD, 2015年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Niobium oxynitrides were prepared by ammonolysis of the amorphous oxide precursors, obtained via citrate gelation, containing either a Mn or Ni additive. The product at 1000 degrees C, even with only 3 at% Ni, was a mixture of epsilon- and TiS-type Nb(N,O), containing a small amount of Ni metal impurity. Mn-containing products were delta-type (Nb,Mn)(N,O) with a NaCl structure. Upon post-annealing under a 0.2 MPa N-2 atmosphere at 1500 degrees C, the crystallinity of the delta-phase improved. The local structure around the substituted Mn2+ was greatly distorted with respect to the regular octahedral site in a delta-type crystal lattice. The microstructure of the post-annealed products containing Mn, as revealed by SEM observation, pointed to the appearance of a liquid phase. The superconductivity (T-c = 15 K) of delta-Nb(N,O) gradually vanished in delta-(Nb,Mn)(N,O), with increasing Mn amount above 5 at% Mn. (C) 2015 Elsevier Ltd. All rights reserved.

Direct synthesis of nearly single-phase BaTaO2N and CaTaO2N powders
Shi-Kuan Sun, Yuji Masubuchi, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 35, 12, 3289, 3294, ELSEVIER SCI LTD, 2015年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Based on the previous work on SrTaO2N [Sun et al. (2014) J. Eur. Ceram. Soc.; doi: 10.1016/j.jeurceramsoc.2014.07.003], a facile method was developed to directly synthesize nearly single-phase powders of BaTaO2N and CaTaO2N by the heat-treatment of alkaline earth metal carbonate and tantalum (oxy)nitride in the atmosphere of N-2, instead of the traditional nitridation of the corresponding oxides in NH3. The submicron-sized BaTaO2N agglomerates were obtained by firing a mixture of BaCO3/Ta3N5 at 850 degrees C in flowing N-2. CaTaO2N product possessed an average particle size of 400 nm in a narrow distribution after firing CaCO3/TaON at 1000 degrees C. CaTaO2N with the higher purity was attained in the usage of TaON than in the case of Ta3N5. (C) 2014 Elsevier Ltd. All rights reserved.

High pressure densification and dielectric properties of perovskite-type oxynitride SrTaO2N
Yuji Masubuchi, Fumio Kawamura, Takashi Taniguchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 35, 4, 1191, 1197, ELSEVIER SCI LTD, 2015年04月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Perovskite-type SrTaO2N was densified using a belt-type high pressure apparatus at 2.5-7.7 GPa with and without sample heating. The relative density of the samples treated at 2.5 GPa was 64% and was increased to 75% in those treated at 7.7 GPa without sample heating. The color of the compact changed from orange to brown with densification and the crystals were fractured to nanometer size grains. The density was increased up to 86% with heating above 800 degrees C at 7.7 GPa and the sample color changed to black, accompanied by electrically conductive nature. The permittivity of compacts that were densified to a relative density of around 75% with heating at 600 degrees C and without sample heating were 200 and 90 at 100 Hz, respectively. (C) 2014 Elsevier Ltd. All rights reserved.

Magnetic properties of the ammonolysis product of alpha-Fe powder containing a small amount of aluminum
Tsugawa, Yuta, Maubuchi, Yuji, Motohashi, Teruki, Kikkawa, Shinichi
Journal of Solid State Chemistry, 222, 111, 114, 2015年02月, ［査読有り］
英語, 研究論文（学術雑誌）

Remarkable oxygen intake/release of BaYMn2O5+δ viewed from high-temperature crystal structure
Teruki Motohashi, Taira Takahashi, Makoto Kimura, Yuji Masubuchi, Shinichi Kikkawa, Yoshiki Kubota, Yoji Kobayashi, Hiroshi Kageyama, Masaki Takata, Susumu Kitagawa, Ryotaro Matsuda
Journal of Physical Chemistry C, 119, 5, 2356, 2363, AMER CHEMICAL SOC, 2015年02月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, © 2015 American Chemical Society. Crystal structure of double-perovskite type BaYMn 2 O 5+δ was studied by high-temperature synchrotron X-ray diffraction (SXRD) under precisely controlled oxygen pressure to gain deeper understanding of the remarkable oxygen intake/release capability of this oxide. The in situ SXRD analysis at 750 °C revealed that this oxide undergoes a distinct structural change upon lowering oxygen pressure, from a slightly oxygen-deficient "δ = 1" phase (BaYMn 2 O 5.89 ; P(O 2 ) = 10 3 Pa) to an oxygen-vacancy ordered "δ = 0.5" phase (BaYMn 2 O 5.51 ; P(O 2 ) = 10 Pa). The BaYMn 2 O 5.89 structure (orthorhombic Cmmm) involves statistical distribution of oxygen vacancies within the yttrium plane. Meanwhile, the BaYMn 2 O 5.51 structure (orthorhombic Icma) contains arrays of pyramidal MnO 5 and octahedral MnO 6 forming an alternate ordering, which is stabilized by a particular Mn 3+ orbital ordering with collective displacements of Y 3+ arrays. Thus, the discontinuous change in the oxygen content can be attributed to the structural reconstruction with oxygen/vacancy redistribution accompanied by yttrium displacement organization.

Processing of dielectric oxynitride perovskites for powders, ceramics, compacts and thin films
Y. Masubuchi, S. -K. Sun, S. Kikkawa
DALTON TRANSACTIONS, 44, 23, 10570, 10581, ROYAL SOC CHEMISTRY, 2015年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Oxynitride perovskites, having oxide and nitride anions together in a compound, are a new class of dielectric material. The shaping process in either bulk ceramics or thin films is an essential factor for investigating and utilizing the dielectric properties of these materials. In this perspective, recent studies on the shaping of dielectric oxynitride perovskites are reviewed with a consideration of the powder preparation and thermal stability for sintering, several sintering methods, ultra-high pressure compaction, and thinfilm formation.

Redox characteristics variations in the cation-ordered perovskite oxides BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1)
Teruki Motohashi, Makoto Kimura, Takeru Inayoshi, Taku Ueda, Yuji Masubuchi, Shinichi Kikkawa
DALTON TRANSACTIONS, 44, 23, 10746, 10752, ROYAL SOC CHEMISTRY, 2015年, ［国際誌］
英語, 研究論文（学術雑誌）, Two series of manganese-based oxygen storage materials, BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1), were synthesized and characterized to clarify cationic substitution effects on the oxygen intake/release behaviors of these materials. The thermogravimetric data revealed that the isovalent substitutions neighboring the active sites for oxygen intake/release are very effective. For BaLnMn(2)O(5+)delta, fully-reduced delta approximate to 0 products with larger Ln ions showed oxygen intake starting at lower temperatures in flowing O-2 gas, resulting in a systematic relationship between the onset temperature and the ionic radius of Ln(3+). Furthermore, the delta vs. P(O-2) plots at 700 degrees C indicated a systematic trend: the larger the ionic size of Ln(3+) is, the larger oxygen contents the Ln-products exhibit. For Ca2Al1-x-GaxMnO5+delta , on the other hand, the temperature-induced oxygen intake/release characteristics appeared to be influenced by Ga-for-Al substitution, where the onset temperatures of oxygen release (upon heating) and oxygen intake (upon cooling) are decreased with the increasing Ga content (x).

Redox characteristics variations in the cation-ordered perovskite oxides BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1)
Teruki Motohashi, Makoto Kimura, Takeru Inayoshi, Taku Ueda, Yuji Masubuchi, Shinichi Kikkawa
DALTON TRANSACTIONS, 44, 23, 10746, 10752, ROYAL SOC CHEMISTRY, 2015年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Two series of manganese-based oxygen storage materials, BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1), were synthesized and characterized to clarify cationic substitution effects on the oxygen intake/release behaviors of these materials. The thermogravimetric data revealed that the isovalent substitutions neighboring the active sites for oxygen intake/release are very effective. For BaLnMn(2)O(5+)delta, fully-reduced delta approximate to 0 products with larger Ln ions showed oxygen intake starting at lower temperatures in flowing O-2 gas, resulting in a systematic relationship between the onset temperature and the ionic radius of Ln(3+). Furthermore, the delta vs. P(O-2) plots at 700 degrees C indicated a systematic trend: the larger the ionic size of Ln(3+) is, the larger oxygen contents the Ln-products exhibit. For Ca2Al1-x-GaxMnO5+delta , on the other hand, the temperature-induced oxygen intake/release characteristics appeared to be influenced by Ga-for-Al substitution, where the onset temperatures of oxygen release (upon heating) and oxygen intake (upon cooling) are decreased with the increasing Ga content (x).

Preparation and luminescence properties of Eu2+-doped oxynitride feldspar SrAl2-xSi2+xO8-xNx
Shi-Kuan Sun, Yuji Masubuchi, Da-Hyeon Go, Young-Sic Kim, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 618, 254, 257, ELSEVIER SCIENCE SA, 2015年01月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Eu2+-doped SrAl2-xSi2+xO8-xNx oxynitride with feldspar structure was prepared using solid state reaction (x = 0-1.0). The phase present, lattice parameter and luminescence properties of the as-prepared phosphors were investigated. The oxynitride samples showed a blue emission shifting from 415 to 453 nm with an increasing x value, having a shoulder peak at 467 nm. The maximum emission intensity was about 2 mol% Eu with a small concentration quenching. (C) 2014 Elsevier B.V. All rights reserved.

Direct synthesis of SrTaO2N from SrCO3/Ta3N5 involving CO evolution
Shi-Kuan Sun, Teruki Motohashi, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 34, 16, 4451, 4455, ELSEVIER SCI LTD, 2014年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, SrTaO2N powder was prepared by a novel reaction between Ta3N5 and SrCO3, instead of the traditional nitridation of SrTaO3.5. The phase evolution and reaction mechanism during the reaction were investigated. The mixed gas evolution of CO, CO2 and N-2 were observed in the heat-treatment of Ta3N5/SrCO3. The SrTaO2N product possessed an average particle size of 330 nm in a narrow distribution with the stoichiometric oxygen and nitrogen content. Its ceramics with various relative density were also fabricated by pressureless sintering of the as-prepared SrTaO2N powder, showing a high sinterability. The fully-annealed SrTaO2N bulks with a RD = 82.8% showed a relatively large dielectric constant and an improved dielectric loss. (C) 2014 Elsevier Ltd. All rights reserved.

Exfoliation of one-dimensional TiO5 chain in K2TiO3
Yuji Masubuchi, Ryo Miyazaki, Hiroki Kikuchi, Teruki Motohashi, Shinichi Kikkawa
DALTON TRANSACTIONS, 43, 36, 13751, 13755, ROYAL SOC CHEMISTRY, 2014年09月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Potassium titanate, K2TiO3, with a chain structure of TiO5 polyhedra was exfoliated in an aqueous nitric acid solution of pH <= 1 and Tyndall scattering due to the colloid formed by the exfoliation was observed. The colloidal particle size measured by dynamic light scattering was approximately 300 nm. The stripe pattern observed by transmission electron microscopy for the aggregated grains after their drying suggested that the TiO5 chains were exfoliated in acid solution. X-ray absorption showed that the coordination polyhedron around Ti4+ changed from a square pyramid in K2TiO3 powder to a distorted octahedron formed with the additional hydronium ions in the acidic solution.

複合アニオン化合物としての酸窒化物の機能性
吉川 信一, 鱒渕 友治
Journal of the Society of Inorganic Materials, Japan : セッコウ・石灰・セメント・地球環境の科学, 21, 372, 308, 313, 無機マテリアル学会, 2014年09月, ［査読有り］, ［最終著者］, ［国内誌］
日本語

Wide Color Variation in SiNO Thin Films Dispersed with Precipitated TiN Nano Particles
Akinori Sawada, Yuji Masubuchi, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 97, 5, 1356, 1358, WILEY-BLACKWELL, 2014年05月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Amorphous thin films of Ti1-ySiy(N,O) with y0.38 were prepared by reactive sputter deposition in a nitrogen atmosphere. Thermal annealing of the films in an ammonia flow above 800 degrees C yielded Si(N,O) amorphous thin films dispersed with precipitated TiN nanosized particles. The film color changed with Si content y and the annealing conditions, from carrot orange to cream yellow in the as-deposited films due to their oxynitride nature, and from dark green to canary yellow and from iron blue to horizon blue at respective annealing temperatures of 800 degrees C and 900 degrees C due to metallic nature of the TiN nanosized particles precipitated in the annealing.

Additive Sintering, Postannealing, and Dielectric Properties of SrTaO2N
Shi-Kuan Sun, Ya-Ru Zhang, Yuji Masubuchi, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 97, 4, 1023, 1027, WILEY, 2014年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The maintaining of the chemical composition and electrical insulativity of SrTaO2N ceramics was investigated during sintering and annealing, using powders prepared by the nitridation of Sr2Ta2O7. Due to the low thermal stability of SrTaO2N, the partial loss of SrO and nitrogen induced the formation of a TaO0.9 impurity after heat-treating at above 1100 degrees C. The sintering additive SrCO3 and postannealing in NH3 were employed to compensate for the loss of SrO and nitrogen to obtain ceramics with the original chemical composition. The as-sintered SrTaO2N ceramics with various relative density (RD) were annealed in NH3 to observe the recovery of color and electrical insulativity. It was found that the inner part of the well-sintered samples with RD=95.1% could not be recovered by annealing, and continued to exhibit semiconducting behavior and a black color. On the other hand, for the as-sintered SrTaO2N ceramics with RD<84%, both the nitrogen content and electrically insulating behavior were completely recovered after annealing. The postannealed SrTaO2N ceramics (RD=83.3%) possessed a relatively large dielectric constant of 450 with a low dielectric loss of less than 0.1 at 100Hz, almost independent of frequency and temperature.

Magnetic softening of Co doped α"-Fe16N2 containing residual Fe-Co alloy prepared in low temperature nitridation
Masubuchi Yuji, Sato Hiroaki, Motohashi Teruki, Kikkawa Shinichi
Journal of The Ceramic Society of Japan, 122, 1424, 288, 291, Ceramic Society of Japan, 2014年04月, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
英語, 研究論文（学術雑誌）, Preparation and magnetic properties were investigated on the Co doped α"-Fe16N2 obtained in low temperature nitridation of bcc Fe1-xCox alloys to change its magnetic coercivity. The alloys were prepared by the reduction of (Fe1-xCox)(3)O-4 obtained by hydrolysis of iron and cobalt acetylacetonate mixture in benzyl alcohol. Fine powder of the pure spinel-type (Fe1-xCox)(3)O-4 was obtained in x = 0-0.05. The oxides were reduced to bcc Fe1-xCox alloy at 400 degrees C in H-2 gas and then nitrided at 150 C for 5 or 8 h under NH3 gas flow. XRD and X-ray absorption spectroscopy suggested the nominal α"-(Fe1-xCox)(16)N-2", similar to α"-Fe16N2" was obtained as a mixture with the residual bcc (Fe1-xCox) alloy at x = 0.03 as in the case of the nitrided product without cobalt. The present nitrided product exhibited a larger magnetization of 217Am(2) kg(-1) and a smaller magnetic coercivity of 30mT at x = 0.03 than those for the present products without the Co doping.

Local structure around the flux pinning centers in superconducting niobium silicon oxynitride (Nb0.87Si0.09□0.04) (N0.87O0.13)
Y. Ohashi, Y. Masubuchi, D. Venkateshwarlu, V. Ganesan, J. V. Yakhmi, T. Yoshida, S. Kikkawa
Journal of Solid State Chemistry, 210, 1, 238, 241, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2014年02月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The superconducting transition temperature of niobium silicon oxynitride (Nb0.87Si0.09□0.04)(N0.87O 0.13) exhibits a gradual reduction from 16.8 K to around 11 K under an increasing applied magnetic field of up to 14 T. This relatively small T c reduction under an applied magnetic field suggests a robustness of its superconducting behavior in comparison to that in the parent niobium oxynitride. It was similar to the flux pinning effect observed in the large magnetic hysteresis of the niobium-silicon oxynitrides in our previous study. Both Si K-edge XANES and 29Si MAS-NMR indicated that the local structure of pinning centers around the silicon atoms close to cationic vacancies was similar to that of Si in amorphous SiO2 in the rock-salt structure of niobium oxynitride. © 2013 Elsevier Inc. All rights reserved.

Synthesis and crystal structure of K2NiF4-type novel Gd1+xCa1-xAlO4-xNx oxynitrides
Yuji Masubuchi, Tomoyuki Hata, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 582, 823, 826, ELSEVIER SCIENCE SA, 2014年01月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Novel gadolinium calcium aluminum oxynitrides, Gd1+xCa1-xAlO4-xNx, were prepared in x = 0.15-0.25 by the solid state reaction of a nitrogen-rich mixture with AlN as an aluminum source; the mixture was sintered twice at 1500 degrees C for 5 h under 0.5 MPa of nitrogen gas. Shift in the optical absorption edge was observed in their diffuse reflectance spectra from 4.46 eV for the oxide (x = 0) to 2.94 eV for the oxynitride at x = 0.2. The crystal structure of Gd1.2Ca0.8AlO3.8N0.2 at x = 0.2 was refined using a synchrotron X-ray diffraction data as a layered K2NiF4-type structure with the I4mm space group. Longer Al-O/N bond lengths in the oxynitride than those in GdCaAlO4 suggest that the nitride ions are in the apical site of aluminum polyhedron, similar to those in Nd2AlO3N. (c) 2013 Elsevier B.V. All rights reserved.

Microwave absorption of epsilon-Fe2O3 precipitated from sputter deposited Fe-Si-O amorphous thin film by thermal annealing
Akinori Sawada, Yuji Masubuchi, Teruki Motohashi, Masahide Sasaki, Shinichi Kikkawa
MATERIALS LETTERS, 115, 198, 200, ELSEVIER, 2014年01月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Granular magnetic thin films were prepared by thermal annealing of rf-sputter-deposited Fe-Si-O amorphous films. The particle size of the precipitated Fe2O3 was controlled to obtain a pure epsilon-phase by adjusting the target chemical composition to an atomic ratio SiO2/Fe2O3=2 and annealing for 1 to 3 h at 900 degrees C. For a film annealed for 100 min, an almost symmetrical ferromagnetic resonance signal was observed, with no evidence of residual ferric ions in the amorphous silica matrix. (C) 2013 Elsevier B.V. All rights reserved.

ペロブスカイト型酸窒化物固溶体の誘電特性および焼結体の作製
鱒渕友治, 吉川信一
村田学術振興財団年報, 28, 2014年

強誘電体・誘電体材料研究の新展開 タンタル酸窒化物ペロブスカイトSrTaO₂Nの結晶構造と誘電特性
本橋輝樹, ZHANG Ya‐Ru, SUN Shi‐Kuan, 鱒渕友治, 吉川信一
セラミックス, 48, 7, 503, 507, 日本セラミックス協会, 2013年07月01日, ［査読有り］, ［国内誌］
日本語

Oxygen Intake/Release Mechanism of Double-Perovskite Type BaYMn2O5+delta (0 <= delta <= 1)
Teruki Motohashi, Taku Ueda, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF PHYSICAL CHEMISTRY C, 117, 24, 12560, 12566, AMER CHEMICAL SOC, 2013年06月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The oxygen intake/release processes of double-perovsldte type BaYMn2O5+delta (0 <= delta <= 1) were investigated from the viewpoints of crystal structure and reaction kinetics. The X-ray diffraction study on the partially oxidized/reduced BaYMn2O5+delta products has revealed a clear indication of successive phase changes among three distinct forms with delta approximate to 0, 0.5, and 1: the oxygen intake/release processes could proceed with nucleation followed by a growth of the generated phase. It has also appeared that the oxygen intake reaction is controlled by surface reaction at 348 <= T <= 403 degrees C, while the oxygen release process is surface-reaction-controlled at 425 <= T <= 550 degrees C and nucleation-process-controlled at 600 <= T <= 750 degrees C. The activation energy for the oxygen intake process at 348 <= T <= 403 degrees C is E-a = 0.27 eV and is much smaller than those reported for any other perovskite-type oxides indicative of great affinity to oxygen molecules.

Hot isostatic press sintering and dielectric properties of SrTaO2N ceramics
Y-R. Zhang, Y. Masubuchi, T. Motohashi, S. Kikkawa, K. Hirota
CERAMICS INTERNATIONAL, 39, 3, 3377, 3380, ELSEVIER SCI LTD, 2013年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, SrTaO2N prepared by a citrate route was capsule hot isostatic press sintered at 196 MPa for 3 h at 1200, 1400 and 1600 degrees C. Densification over 80% was attained for all the sintered bodies with partial reduction, which was observed as a change of color from brown to dark gray. Exaggerated grain growth was observed with some amount of open pore for the product sintered at 1400 degrees C. The sample was successfully returned to the brown insulator color after annealing in ammonia flow at 1000 degrees C. The resultant SrTaO2N ceramics exhibited a considerably high relative dielectric permittivity of 7.8 x 10(3) at 10(2) Hz. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The 66th CerSJ Awards for Advancements in Ceramic Science and Technology : Synthesis, structure and properties of new functional oxynitride ceramics
MASUBUCHI Yuji
Journal of the Ceramic Society of Japan = 日本セラミックス協会学術論文誌, 121, 1410, 142, 149, The Ceramic Society of Japan - 日本セラミックス協会, 2013年02月, ［査読有り］, ［招待有り］, ［筆頭著者, 責任著者］, ［国内誌］
英語, 研究論文（学術雑誌）, Novel metal oxynitrtides have been prepared by nitridation of amorphous metal oxide precursors obtained through citrate route. Their crystal structure, especially in O/N distribution and local bonding characteristics has been analyzed by using neutron diffraction, X-ray absorption and transmission electron microscopy, to investigate their electric and optical properties. In dielectric SrTaO2N, crystal structure refinement suggested the short range O/N ordering and local tilting of cis-TaO4N2 octahedra, resulting in its unusual large permittivity. Its dense ceramics were sintered with SrCO3 additive and exhibited superior dielectric constant above 1 x 10(4) at room temperature. New biphasic wurtzite and zinc-blende structure of gallium oxynitride nanowire was observed by using transmission electron microscopy. As-grown long gallium oxynitride nanowire exhibited a characteristic broad UV emission at 4.3 eV in its cathodoluminescene spectrum. New oxynitride phosphor having magnetoplumbite structure, LaAl12(O,N)(19):Eu showed photoluminescence emission peak splitting due to Eu2+ site splitting to two crystallographic sites induced by the two kinds of anions in its crystal structure.

Oxygen Storage Capability of Brownmillerite-type Ca2AlMnO5+delta and Its Application to Oxygen Enrichment
Teruki Motohashi, Yuka Hirano, Yuji Masubuchi, Kazunori Oshima, Tohru Setoyama, Shinichi Kikkawa
CHEMISTRY OF MATERIALS, 25, 3, 372, 377, AMER CHEMICAL SOC, 2013年02月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The oxygen storage capability was investigated for Ca-2(AlxMn1-x)(2)O5+delta (0.50 <= x <= 0.67) with a Brownmillerite-type structure. This oxide can store/release a large amount of excess oxygen (similar to 3.0 wt %) topotactically in response to variations in temperature and the surrounding atmosphere in a highly reversible manner. The capacity and response of oxygen storage are remarkable only in the vicinity of x = 0.50, that is, Ca2AlMnO5+delta, and rapidly deteriorated as the Al content increases. Owing to the high sensitivity in terms of oxygen nonstoichiometry, Ca2AlMnO5+delta exhibits oxygen intake/release ability when temperature swing between 500 and 700 degrees C is applied. With this characteristic feature of this oxide, a facile method for oxygen enrichment is demonstrated.

Crystal structure and magnetic properties of "alpha ''-Fe16N2" containing residual alpha-Fe prepared by low-temperature ammonia nitridation
S. Yamashita, Y. Masubuchi, Y. Nakazawa, T. Okayama, M. Tsuchiya, S. Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 194, 76, 79, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2012年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Slight enhancement of saturation magnetization to 219 A m(2) kg(-1) was observed from 199 A m(2) kg(-1) for the original alpha-Fe on the intermediate nitrided mixture of "alpha ''-Fe16N2" with residual alpha-Fe among the low temperature ammonia nitridation products under 5 T magnetic field at room temperature. The value changed not linearly against the yield as had been expected. Crystal structure refinement indicated that the phase similar to alpha ''-Fe16N2 had deviations on its lattice constants and positional parameters, compared to previously reported values for alpha ''-Fe16N2. Spin-polarized total energy calculations were performed using the projector-augmented wave method as implemented in the Vienna ab-initio simulation package (VASP) to calculate magnetic moment on the refined crystal structure of the intermediate "alpha ''-Fe16N2". The calculations supported the observed magnetization enhancement in the intermediate nitridation product. (C) 2012 Elsevier Inc. All rights reserved.

Crystal Structure and Superconducting Properties of Hexagonal Lithium-Niobium Oxynitride
Teruki Motohashi, Masahiko Ito, Yuji Masubuchi, Makoto Wakeshima, Shinichi Kikkawa
INORGANIC CHEMISTRY, 51, 20, 11184, 11189, AMER CHEMICAL SOC, 2012年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, A hexagonal oxynitride (Li-0.88 square(0.12))-Nb-3.0(O0.13N0.87)(4) was synthesized through ammonia nitridation of LiNb3O8. The structural analysis revealed that this oxynitride consists of alternate stacking of octahedral and prismatic layers with different Li/Nb ratios: significant amounts of Li and Nb atoms (Li/Nb = 43/57) coexist in the octahedral layer, while the prismatic site is preferentially occupied by Nb (Li/Nb = 3/97). A metallic behavior was accompanied by an abrupt drop of electrical resistivity at about 3 K. Furthermore, large diamagnetism and specific-heat anomaly were observed below this temperature, suggesting the appearance of superconductivity in the Li-Nb oxynitride.

Nanowire of hexagonal gallium oxynitride: Direct observation of its stacking disorder and its long nanowire growth
Yuji Masubuchi, Ryohei Yamaoka, Tetsuya Tohei, Teruyasu Mizoguchi, Yuichi Ikuhara, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 32, 9, 1989, 1993, ELSEVIER SCI LTD, 2012年07月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The crystal structure of gallium oxynitride nanowire was investigated by using scanning transmission electron microscopy. Gallium oxynitride nanowire was directly observed to have a biphasic wurtzite and zinc-blende structure. There was a stacking disorder of several atomic layers between the two phases. The new biphasic nanowire formed due to the presence of Ni in starting material because its nitride has a zinc-blende structure whereas gallium oxynitride has the wurtzite structure. Crystal growth of gallium oxynitride nanowires was studied using seed crystals. Seed crystals and amorphous gallium oxide precursors were annealed under different ammonia flow rates to grow gallium oxynitride nanowires. The nanowires grew to length of 150 mu m but they did not grow laterally when the ammonia flow rate was 50 mL/min. (C) 2011 Elsevier Ltd. All rights reserved.

Sintering and dielectric properties of perovskite SrTaO2N ceramics
Ya-Ru Zhang, Teruki Motohashi, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 32, 6, 1269, 1274, ELSEVIER SCI LTD, 2012年06月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Single-phase perovskite oxynitride SrTaO2N ceramics were prepared by pressureless sintering at 1400 degrees C under a nitrogen atmosphere, using 5 wt% of SrCO3 or La2O3 as a sintering additive. In contrast, SrTaO2N bulks without additives contained TaC and Ta3N5 impurities. Sintering in nitrogen led to oxygen/nitrogen deficiencies in the oxynitride, while post annealing in flowing ammonia was effective to eliminate the anion vacancies. The introduction of additives significantly improved the sinterability of SrTaO2N ceramics. A relative density of >90% in the bulk was achieved with a highly dense micro;tructure with smaller grain sizes. The SrTaO2N bulk with SrCO3 additive exhibited superior dielectric performance with a high relative permittivity (epsilon(r) =1.0 x 10(4)) and dissipation factor (tan delta = 0.039) at a frequency of 1 MHz. (C) 2011 Elsevier Ltd. All rights reserved.

SITE OCCUPANCIES OF NITRIDE AND OXIDE IONS IN STRONTIUM NIOBIUM OXYNITRIDE PEROVSKITES
T. Komiyama, Y. Masubuchi, T. Motohashi, S. Kikkawa
INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 25, 31, 4167, 4170, WORLD SCIENTIFIC PUBL CO PTE LTD, 2011年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Crystal structure was refined on Sr-Nb and Sr(La)-Nb oxynitride perovskites prepared through citrate route by using neutron diffraction. The former had the composition of SrNbO2.11N0.89 and crystallized in I4/mcm with a = 0.57099(2) nm, c = 0.81015(5) nm having excess oxide ions in apical 4a site around Nb being compared to the cis-TaO4N2 octahedra in SrTaO2N. The latter crystallized in the same space group with Sr0.81La0.19 having a = 0.57126(3) nm, c = 0.81055(6) nm. It was assumed that Sr0.81La0.19O1.90N1.10 has similar O/N occupancy in both apical 4a and equatorial 8h sites. The La substitution made the O/N occupancies equilibrated around Nb. The niobium valency was slightly less than five in these oxynitride perovskites.

Crystal growth and characterization of gallium oxynitride nanowires grown on seed crystals
Yuji Masubuchi, Ryohei Yamaoka, Teruki Motohashi, Kazuhiko Kirihara, Woong Lee, Kentaro Watanabe, Takashi Sekiguchi, Shinichi Kikkawa
JOURNAL OF CRYSTAL GROWTH, 337, 1, 87, 92, ELSEVIER, 2011年12月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Nanowires of gallium oxynitride with wurtzite type structure were grown using seed crystals obtained by ammonia nitridation of an amorphous gallium oxide precursor containing 3 at% nickel additive. The seed crystals on a silica substrate were annealed with the amorphous gallium oxide precursor under ammonia flow to grow gallium oxynitride nanowires. The nanowires grew to lengths of about 150 mu m along the seed crystals parallel to the hexagonal c-plane at 750 and 800 degrees C but they did not grow in the lateral direction. When the growth temperature was increased above 900 degrees C, the growth direction gradually changed to become parallel with the c-axis with a copresenting of gallium-nitride-like crystals. Room-temperature cathodoluminescence spectra of nanowires grown at 800 degrees C exhibited strong blue emission at 2.69 eV along with weak band-edge emission at 3.39 eV, similar to those of GaN. The latter emission was intense for nanowires grown at 1000 degrees C, which had an improved crystallinity and a higher nitride/oxide ion ratio. Nanowires grown at 750 and 900 degrees C exhibited persistent photoconductivity under UV irradiation at 393 nm. (C) 2011 Elsevier B.V. All rights reserved.

Crystallization and magnetic property of iron oxide nanoparticles precipitated in silica glass matrix
Y. Masubuchi, Y. Sato, A. Sawada, T. Motohashi, H. Kiyono, S. Kikkawa
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, 31, 14, 2459, 2462, ELSEVIER SCI LTD, 2011年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Crystallization and magnetic property of Fe(2)O(3) nanoparticle precipitated in SiO(2) matrix was investigated. Fe(2)O(3)/SiO(2) nanocomposite thin film was obtained by annealing of the amorphous Fe-Si-O thin film deposited by RF-magnetron sputtering of (alpha-Fe(2)O(3))(1-x)/(SiO(2))(x) composite targets. The Fe(2)O(3) crystallite size increased with decreasing SiO(2) area ratio, x of the target and increasing annealing temperature epsilon-Fe(2)O(3) with the crystallite size of 20-30 nm was obtained after annealing the film deposited in SiO(2) area ratio, x = 0.33-0.42 at 900 degrees C. Lower SiO(2) area ratio (x) than 0.25 and higher annealing temperature resulted in precipitation of alpha-Fe(2)O(3) with the larger crystallite size than 40 nm. In the case of SiO(2) area ratio, x >= 0.50, the annealed film was amorphous and showed higher magnetization and smaller coercivity due to the precipitation of very small crystalline gamma-Fe(2)O(3). The epsilon-Fe(2)O(3)/SiO(2) composite thin film showed ferromagnetic hysteresis with coercive force of 0.14 T. (C) 2011 Elsevier Ltd. All rights reserved.

Magnetite/maghemite mixture prepared in benzyl alcohol for the preparation of α"-Fe16N2 with α-Fe
Masubuchi Y, Yamashita S, Motohashi T, Kikkawa S, Niederberger M
Journal of the European Ceramic Society, 31, 14, 2471, 2474, Elsevier, 2011年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Fine powder of iron oxide has been required in the preparation of ferromagnetic α"-Fe16N2 powder in low temperature nitridation. Its particle size of about 30 nm and less humidity content was crucial in the reproducible α"-Fe16N2 preparation in high yield. Magnetite and maghemite mixture with about 40 nm particle size was obtained by the reaction of iron acetylacetonate Fe(acac)3 of more than 4 g dissolved in 40 mL benzyl alcohol. It was reduced to α-Fe in hydrogen at 400 ℃. Particle size of the α-Fe was 300 nm in the reduction of iron oxides obtained from 2 g of Fe(acac)3. It decreased to ...

Enhanced oxygen intake/release kinetics of BaYMn2O5+delta fine powders prepared by a wet-chemical route
Teruki Motohashi, Taku Ueda, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, 119, 1395, 894, 897, CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI, 2011年11月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The effect of grain size on the oxygen intake/release kinetics were investigated for double-perovskite type BaYMn2O5+delta (delta = 0.0- 1.0). The preparation of BaYMn2O5+delta with larger specific surface area was achieved by low-temperature firing (down to 900 degrees C) of precursors obtained from a wet-chemical route. The oxygen intake/release rates at 500 degrees C were found to increase significantly in the resultant BaYMn2O5+delta fine powders, indicating a key role of the powder surface in the oxygen intake/release processes. (C) 2011 The Ceramic Society of Japan. All rights reserved.

Ammonolysis of HTiNbO5-n-Propylamine Intercalation Compound
Yuji Masubuchi, Chihiro Yamakami, Teruki Motohashi, Shinichi Kikkawa
CHEMISTRY LETTERS, 40, 11, 1238, 1239, CHEMICAL SOC JAPAN, 2011年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
英語, 研究論文（学術雑誌）, The ammonolysis reaction to form (Ti,Nb)N was enhanced by the use of HTiNbO5-n-propylamine intercalation compound as a starting material and compared with that for a simple mixture of TiO2 and Nb2O5. The ammonolysis product formed at 1200 degrees C was a superconductor (T-c = 15K) with a rock-salt crystal structure having many structural defects along the stacking direction of the intercalation compound.

Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting
Yuji Masubuchi, Tomoyuki Hata, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 184, 9, 2533, 2537, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2011年09月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Eu-doped lanthanum aluminum oxynitride (LaAl12(O,N)(19)) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440 nm with a shoulder at 464 nm under excitation at 254 nm. Isostructural Eu-doped calcium aluminum oxide (CaAl12O19) exhibited a single emission peak at 415 nm. Structural refinement using neutron powder diffraction indicated that the lanthanum site occupied partially by Eu2+ splits into 2d and 6h sites in the aluminum oxynitride. The longer emission and the shoulder peak in the former aluminum oxynitride were observed in relation to the increasing covalency as well as crystal field splitting around doped Eu2+ induced by site splitting involved with the two kinds of anions. (C) 2011 Elsevier Inc. All rights reserved.

Preparation, crystal structure, and superconductive characteristics of new oxynitrides (Nb1-xMx)(N(1-y)o(y)) where M = Mg, Si, and x approximate to y
Yoshio Ohashi, Teruki Motohashi, Yuji Masubuchi, Toshihiro Moriga, Keiichiro Murai, Shinichi Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 184, 8, 2061, 2065, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2011年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, New niobium oxynitrides containing either magnesium or silicon were prepared at 1000 degrees C by ammonia nitridation of oxide precursors obtained via the citrate route. The products had rock-salt type crystal structures. Crystallinity was improved by annealing in 0.5 MPa N-2 and the final compositions were (Nb0.95Mg0.05)(N0.92O0.08) at 1500 degrees C and (Nb0.87Si0.09 square(0.04))(N0.87O0.13) at 1200 degrees C. The magnesium and oxide ions partially co-substitute the niobium and nitride ions in the octahedral sites of the delta-NbN lattice, respectively. Silicon ions were also successfully doped together with oxide ions into the rock-salt type NbN lattice. The Si doped product exhibited relatively large displacement at the octahedral sites and was accompanied by a small amount of cation vacancies. Superconductivity was improved by annealing to obtain critical temperatures/volume fractions of T-c = 17.6 K/100% for Mg- and T-c = 16.2 K/95% for the Si-doped niobium oxynitrides. (C) 2011 Elsevier Inc. All rights reserved.

Local anionic ordering and anisotropic displacement in dielectric perovskite SrTaO2N
Ya-Ru Zhang, Teruki Motohashi, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, 119, 1391, 581, 586, CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI, 2011年07月, ［査読有り］, ［国内誌］
英語, 研究論文（学術雑誌）, The perovskite oxynitride SrTaO2N as a promising candidate for lead-free dielectric materials has been studied with a special emphasis on the structural characterization using neutron powder diffraction. SrTaO2N powders were prepared by means of ammonia nitridation via precursors obtained from a soft chemistry method and a solid state reaction route. All the products crystallized in tetragonal I4/mcm space group with only slight variation in the lattice constant, e.g., a = 5.7023(1)angstrom and c = 8.0786(1)angstrom for the soft-chemistry derived sample. Neutron diffraction analysis suggested the short-range O/N ordering involving a cis configuration in TaO4N2 octahedra together with large anionic displacement within the ab plane on their axial position in the average crystal lattice. These facts are associated with local tilting of the TaO4N2 octahedra which is likely to play a key role in the unusual dielectric behavior of SrTaO2N. (C)2011 The Ceramic Society of Japan. All rights reserved.

Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2
T. Motohashi, Y. Sugimoto, Y. Masubuchi, T. Sasagawa, W. Koshibae, T. Tohyama, H. Yamauchi, S. Kikkawa
PHYSICAL REVIEW B, 83, 19, 195128, AMER PHYSICAL SOC, 2011年05月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Thermoelectric properties of the layered cobalt oxide system LixCoO2 were investigated in a wide range of Li compositions, 0.98 >= x >= 0.35. Single-phase bulk samples of LixCoO2 were successfully obtained through electrochemical deintercalation of Li from the pristine LiCoO2 phase. While LixCoO2 with x >= 0.94 is semiconductive, the highly Li-deficient phase (0.75 >= x >= 0.35) exhibits metallic conductivity. The magnitude of the Seebeck coefficient at 293 K (S-293K) significantly depends on the Li content (x). The S-293K value is as large as +70 up to +100 mu V/K for x >= 0.94, and it rapidly decreases from +90 mu V/K to +10 mu V/K as x is lowered within a Li composition range of 0.75 >= x >= 0.50. This behavior is in sharp contrast to the results of x <= 0.40 for which the S-293K value is small and independent of x (+10 mu V/K), indicating that a discontinuous change in the thermoelectric characteristics takes place at x = 0.40-0.50. The unusually large Seebeck coefficient and metallic conductivity are found to coexist in a narrow range of Li composition at about x = 0.75. The coexistence, which leads to an enhanced thermoelectric power factor, may be attributed to unusual electronic structure of the two-dimensional CoO2 block.

Microstructure formation during the annealing of iron nitrides
R. Saito, Y. Masubuchi, T. Motohashi, S. Kikkawa, M. Sasaki
MATERIALS RESEARCH BULLETIN, 46, 4, 547, 550, PERGAMON-ELSEVIER SCIENCE LTD, 2011年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The thermal metastability of iron nitride was exploited to fabricate thin-film microstructures applicable to left-handed metamaterials. A granular thin film containing dispersed iron particles was prepared by post-annealing an rf-sputter-deposited Fe(0.5)Al(0.5)N thin film with a wurtzite-type structure in a nitrogen atmosphere at 450 degrees C. The obtained samples showed magnetic resonance in the microwave region. Laser direct writing was also applied in a nitrogen atmosphere to an rf-sputter-deposited Fe(0.7)Al(0.3)N thin film. 200 mu m-wide, 300 Omega cm iron metal lines were drawn in a host nitride film of approximately 2 k Omega cm. Combining and optimizing the above negative permeability and permittivity values should provide left-handed materials with a negative refractive index. (C) 2010 Elsevier Ltd. All rights reserved.

Electron Transport Under Magnetic Field in Insulating Hematite Composites with Spinel Ferrite
Yuji Masubuchi, Makoto Minoya, Takashi Takeda, Shinichi Kikkawa
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 94, 3, 765, 770, WILEY-BLACKWELL, 2011年03月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The magnetoresistance (MR) of polycrystalline composites of ferromagnetic (FM) (M,Fe)(3)O(4) (M=Mn, Co, Ni, and Zn) spinel ferrite and weak FM alpha-Fe(2)O(3) insulator with spin canting was investigated. Sample disks were prepared by conventional solid-state sintering of alpha-Fe(2)O(3), with either Mn(2)O(3), Co(3)O(4), NiO, or ZnO in a mixing ratio of M/Fe=x/(3-x) at 1473 K for 10 h under Ar or air atmospheres. The largest MR ratios of 2.02% at room temperature and 11.7% at 77 K were observed under a magnetic field of 0.5 T for the (Mn,Fe)(3)O(4)/alpha-Fe(2)O(3) composite (x=0.25) sintered under air. The temperature dependence of the electrical resistivity showed a ln()proportional to T -1/2 relationship, which suggests tunneling electron conduction in the granular composite. The MR ratio changed with the magnetization of the (M,Fe)(3)O(4) spinel ferrite, with a maximum at 2.02% where the (Mn,Fe)(3)O(4) ferrite grains were separated with the alpha-Fe(2)O(3) barrier of several micrometer thickness. The MR may be attributed to spin polarization in the ferrite grains coupled with the alpha-Fe(2)O(3) insulating barrier, where its spins are slightly canting in strong anti-FM interaction.

希土類ケイ酸塩酸素アパタイト中の酸化物イオン伝導経路
奥寺 浩樹, 鱒渕 友治, 吉川 信一
日本結晶学会誌, 53, 1, 86, 90, 日本結晶学会, 2011年02月28日, ［査読有り］, ［国内誌］
日本語, Apatite-type RE9.33(SiO4)6O2 rare-earth silicate compounds are of great interest for their oxide ion conductivity at moderate temperatures. Crystallographic space group and structural parameters of La/Nd9.33(SiO4)6O2 were investigated based on single-crystal X-ray diffraction data at room temperature for La9.33(SiO4)6O2 and at various temperatures from 150 to 900 K for Nd9.33(SiO4)6O2. Based on the most accurate diffraction data to date, these compounds have an apatite prototype structure (space group P63/m) with no symmetry lowering, site splitting nor interstitial oxide ion in the structu...

Microwave-Assisted Nonaqueous Sol-Gel Chemistry for Highly Concentrated ZnO-Based Magnetic Semiconductor Nanocrystals
Idalia Bilecka, Li Luo, Igor Djerdj, Marta D. Rossell, Marko Jagodic, Zvonko Jaglicic, Yuji Masubuchi, Shinichi Kikkawa, Markus Niederberger
JOURNAL OF PHYSICAL CHEMISTRY C, 115, 5, 1484, 1495, AMER CHEMICAL SOC, 2011年02月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Various transition metal (TM) doped zinc oxide nanopartides with the composition TMxZn1-xO (TM = V, Mn, Fe, Co, and Ni; x = 0.01-0.3) were prepared by a microwave-assisted nonaqueous sol-gel route in benzyl alcohol within a few minutes. The high doping levels in the range 20-30 atom % achieved for Co and Fe provide a promising opportunity to study the magnetic properties of such potential diluted magnetic semiconductors. However, only Fe0.2Zn0.8O was ferromagnetic at room temperature. The Co-doped sample showed Curie-Weiss behavior up to a doping level of 30 atom %. According to X-ray absorption fine structure (XAFS) measurements, at high doping levels the Fe-doped ZnO samples contain an increasing fraction of Fe3+ ions (in addition to Fe2+), whereas Co is predominantly in the oxidation state of +2. Clustering of Fe ions into amorphous ferromagnetic Fe3O4 within the ZnO host and the magnetic interactions between the Fe3O4 regions is a possible explanation for the ferromagnetic properties.

Silver delafossite nitride, AgTaN2?
Akira Miura, Michael Lowe, Brian M. Leonard, Chinmayee V. Subban, Yuji Masubuchi, Shinichi Kikkawa, Richard Dronskowski, Richard G. Hennig, Hector D. Abruna, Francis J. DiSalvo
JOURNAL OF SOLID STATE CHEMISTRY, 184, 1, 7, 11, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2011年01月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, A new silver nitride, AgTaN2, was synthesized from NaTaN2 by a cation-exchange reaction, using a AgNO3-NH4NO3 flux at 175 degrees C Its crystal structure type is delafossite (R (3) over barm) with hexagonal lattice parameters of a=3.141(3) angstrom, c=18.81(2) angstrom, in which silver is linearly coordinated to nitrogen. Energy dispersive X-ray analysis and combustion nitrogen/oxygen analysis gave a composition with atomic ratios of Ag:Ta:N:O as 1.0:1.2(1):2.1(1):0.77(4), which is somewhat Ta rich and indicates some oxide formation. The X-ray photoelectron spectroscopy analysis showed a Ta- and O-rich surface and transmission electron microscope observation exhibited aggregates of ca. 4-5 nm-sized particles on the surface, which are probably related to the composition deviation from a AgTaN2. The lattice parameters of stoichiometric AgTaN2 calculated by density functional theory agree with the experimental ones, but the possibility of some oxygen incorporation and/or silver deficiency is not precluded. (C) 2010 Elsevier Inc. All rights reserved.

Synthesis, thermal stability, and oxygen intake/release characteristics of YBa(Co1-xAlx)(4)O7+delta
Takafumi Komiyama, Teruki Motohashi, Yuji Masubuchi, Shinichi Kikkawa
MATERIALS RESEARCH BULLETIN, 45, 10, 1527, 1532, PERGAMON-ELSEVIER SCIENCE LTD, 2010年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The YBaCo4O7+d(Y-114) phase has recently attracted interests as a potential oxygen storage material due to its oxygen intake/release capability at 200-400 degrees C. Nevertheless, thermal instability of Y-114 has been an obstacle for future applications, since this compound immediately starts to decompose when the sample is heated at 700-800 degrees C in oxygen-rich atmosphere. Here we demonstrate that Al-for-Co substitution in Y-114 drastically enhances the thermal stability. Substituting only 10 at.% of aluminum for cobalt in Y-114 essentially suppresses the decomposition reaction seen at 700-800 degrees C, while well retaining its remarkable oxygen intake/release capability at 200-400 degrees C. It is also revealed that the addition of aluminum effectively reduces the particle size. The Al-substituted Y-114 products exhibit superior oxygen intake/release response to the Al-free products upon switching the atmosphere between O-2 and N-2. (C) 2010 Elsevier Ltd. All rights reserved.

Humidity effects in Fe16N2 fine powder preparation by low-temperature nitridation
Kohetsu Yamanaka, Yuki Onuma, Shohei Yamashita, Yuji Masubuchi, Takashi Takeda, Shinichi Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 183, 9, 2236, 2241, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2010年09月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Low-temperature nitridation has been reported to produce ferromagnetic alpha ''-Fe16N2 by ammonia nitridation of alpha-Fe fine powder, which was obtained from the reduction of vapor-grown gamma-Fe2O3. The effects of humidity during this preparation were investigated in the present study. alpha ''-Fe16N2 was inconsistently obtained, and at low yield, from Fe3O4 fine powder (MT-40) prepared from aqueous solution. Reducing the adsorbed water content in the iron oxide starting powder resulted in improved reproducibility of the alpha ''-Fe16N2 yield of the nitridation. The use of a smaller-diameter reaction tube, less than 25 mm in diameter, enabled more reproducible preparation from vapor-grown gamma-Fe2O3 powder (CI-30). The reaction yield was further improved by using high-quality ammonia with a water content of <= 0.05 ppm. Minimizing the humidity made it possible to obtain a fine powder with a high alpha ''-Fe16N2 content. Enhancement of the magnetization to 210 emu g(-1) at room temperature was observed from a nitrided mixture of alpha ''-Fe16N2 with residual alpha-Fe, compared to 199 emu g(-1) for an alpha-Fe fine powder reduced from gamma-Fe2O3. However, excess nitrogen and residual oxygen in the nitrided products reduced the magnetization below the value of alpha-Fe powder after nitridation. The magnetization was enhanced in nitrided products with a nitrogen content slightly below the stoichiometric amount for alpha ''-Fe16N2. (C) 2010 Elsevier Inc. All rights reserved.

Crystal structure and superconductive characteristics of Nb0.89Al0.11 oxynitrides
Yoshio Ohashi, Teruki Motohashi, Yuji Masubuchi, Shinichi Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 183, 7, 1710, 1714, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2010年07月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, The crystal structure and superconductive characteristics of the niobium-aluminum oxynitrides were investigated. Single-phase products were successfully obtained starting from a cation ratio of Nb0.89Al0.11. The as-nitrided product crystallized in a cation-deficient rock-salt type structure with a chemical formula of (Nb0.60Al0.08 square(0.32))(O0.21N0.79), while annealing at 1773 K under a nitrogen pressure of 0.5 MPa led to a highly crystallized product with a simple rock-salt type structure represented as (Nb0.89Al0.11)(O0.17N0.85). Upon post-annealing, both the critical temperature (T-c) and the superconductive volume fraction (V-SC) of the oxynitride were significantly enhanced from T-c approximate to 7 K and V-SC=23% for the as-nitrided product to T-c = 17.3 K and V-SC=91% for the post-annealed product. (C) 2010 Elsevier Inc. All rights reserved.

Remarkable Oxygen Intake/Release Capability of BaYMn2O5+delta: Applications to Oxygen Storage Technologies
Teruki Motohashi, Taku Ueda, Yuji Masubuchi, Makoto Takiguchi, Tohru Setoyama, Kazunori Oshima, Shinichi Kikkawa
CHEMISTRY OF MATERIALS, 22, 10, 3192, 3196, AMER CHEMICAL SOC, 2010年05月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Here, we report the remarkable oxygen intake/release capability of a double perovskite BaYMn2O5+delta. This oxide rapidly stores/releases a large amount of oxygen (> 3.7 wt %) at moderate temperatures in a perfectly reversible manner. The oxygen intake/release behaviors of BaYMn2O5+delta are clearly beyond those of any conventional oxides in terms of the magnitude and sharpness of the processes. It also appeared that this oxide exhibits a significant catalytic activity for nameless combustions of hydrocarbons, presumably owing, to its oxygen-storage ability.

Indium and gallium oxynitrides prepared in the presence of Zn2+ by ammonolysis of the oxide precursors obtained via the citrate route
Azumi Miyaake, Yuji Masubuchi, Takashi Takeda, Shinichi Kikkawa
MATERIALS RESEARCH BULLETIN, 45, 4, 505, 508, PERGAMON-ELSEVIER SCIENCE LTD, 2010年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Ammonia nitridation of indium and gallium oxide precursors obtained through a soft solution route led to their oxynitrides [In-0.97 square(0.03)][N0.92O0.08] at 660 degrees C and [Ga-0.89 square(0.11)][N0.66O0.34] at 850 degrees C, respectively, where E] refers to a In or Ga vacancy. Cation vacancies in their wurtzite-type lattice were eliminated in similar preparations with the co-presence of Zn2+ by forming complete solid solutions of (InN)(1-x)(ZnO)(x) and (GaN)(1-y)(ZnO)(y). The optical absorption edge shape was found to be relatively steep at the solid Solution limits of x approximate to 0.23 and y approximate to 0.33 compared to the case without zinc. (C) 2009 Elsevier Ltd. All rights reserved.

Synthesis and photoluminescence of blue-emitting 15R-sialon:Eu2+ phosphors
X. W. Zhu, Y. Masubuchi, T. Motohashi, S. Kikkawa, T. Takeda
JOURNAL OF ALLOYS AND COMPOUNDS, 496, 1-2, 407, 412, ELSEVIER SCIENCE SA, 2010年04月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, This paper reports the synthesis and photoluminescence of Eu2+-doped 15R-sialon (SiAl4O2N4) phosphors by firing the powder mixture of Si3N4, Al2O3, AIN and Eu2O3 at 1700-1900 degrees C for 3h under a nitrogen pressure of 0.5 MPa. Single-phase 15R-sialon:Eu2+ phosphors could be obtained by controlling Eu concentration at 1800-1850 degrees C. 15R-sialon:Eu2+ phosphors exhibit blue emission spectra consisting of a broad band with a maximum at about 445 nm and a shoulder at about 465 nm under UV light excitation (250-400 nm). The critical Eu concentration is about 0.5 mol%. The emission spectra and biexponential fluorescence decay suggest that there are two different kinds of N/O coordinations around Eu2+ ions in 15R-sialon. The 15R-sialon:Eu2+ phosphor has small thermal quenching and good chromaticity of x=0.16 and y=0.09 for blue emission. (C) 2010 Elsevier B.V. All rights reserved.

OXYNITRIDES AS NEW FUNCTIONAL CERAMIC MATERIALS
Shinichi Kikkawa, Teruki Motohashi, Yuji Masubuchi
ADVANCES IN MULTIFUNCTIONAL MATERIALS AND SYSTEMS, 216, 105, 111, AMER CERAMIC SOC, 2010年, ［査読有り］, ［国際誌］
英語, 研究論文（国際会議プロシーディングス）, SiAION has been only one oxynitride as a useful ceramic material. It has been used as structural ceramics. Recently it has found out an additional application as phosphor materials in light emitting diode. We have developed a new preparation method through solution route for various kinds of metal oxynitrides. Magnetic and optical materials were found out in gallium oxynitride and its nanofiber was also obtained. New phosphor material could be developed in aluminum oxynitride. Structural investigation was performed on EuTaO2N perovskite as a model for potential lead-free dielectric ATaO(2)N (A=Sr, Ba). Possible new superconductor was also found out in niobium related oxynitride.

Sputter Deposition of Fe-Co Nitride for Ferromagnetic Granular Nitride Thin Film
K. Sakon, Y. Hirokawa, Y. Masubuchi, S. Kikkawa
MULTISCALE, MULTIFUNCTIONAL AND FUNCTIONALLY GRADED MATERIALS, 631-632, 327, 331, TRANS TECH PUBLICATIONS LTD, 2010年, ［査読有り］, ［国際誌］
英語, 研究論文（国際会議プロシーディングス）, Sputter deposited Fe(0.7)Co(0 3) nitride thin film had zinc blende structure. It was thermally decomposed completely back to the ferromagnetic Fe(0.7)Co(0.3) alloy above 400 degrees C. As-deposited nitride thin films obtained in cosputtering of (Fe(0.7)Co(0.3))(1-x)Al(x) composite target with nitrogen sputter gas were solid solutions with zinc blende (x <= 0.44) and wurtzite (x>0.5) type structure, respectively. The largest magneto resistance ratio of 0.24% was observed on the Fe(0.7)Co(0.3) alloy particles dispersed in AlN thin film obtained by thermal decomposition of the nitride solid solution with x=0.66 at 500 degrees C.

The z value dependence of photoluminescence in Eu^[2+]-doped β-SiAlON (Si_[6-z]AlzOzN_[8-z]) with 1 ≤ z ≤ 4
Zhu X. W, Masubuchi Y, Motohashi T, Kikkawa S
Journal of Alloys and Compounds, 489, 1, 157, 161, Elsevier B.V., 2010年01月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Eu^[2+]-doped β-SiAlON (Si_[6-z]AlzOzN_[8-z]) phosphors with 1 ≤ z ≤ 4 were synthesized by gas pressure sintering. The emission spectra exhibit two broad bands with maxima at about 415 nm (violet) and 540 nm (green) under ultraviolet excitation. The green emission is dominant at z ≤ 2, while the violet emission becomes dominant at z > 2. The combination of two emission bands in a compound could lead to a white emission in Eu^[2+]-doped β-SiAlON with 2 < z ≤ 3.

Preparation of gallium oxynitride powder and its nanofibers by the nitridation of a gallium oxide precursor doped with nickel or cobalt obtained via the citrate route
A. Miyaake, Y. Masubuchi, T. Takeda, T. Motohashi, S. Kikkawa
DALTON TRANSACTIONS, 39, 26, 6106, 6111, ROYAL SOC CHEMISTRY, 2010年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Acicular crystals were grown in gallium oxynitride powder prepared by ammonia nitridation of amorphous gallium oxide precursors containing less than 5 at% of either Ni or Co, via the citrate route. The crystals were several tens of nanometres wide, several micrometres long, and grown in the temperature range 750 to 850 degrees C in a flow of ammonia of less than 200 mL min(-1). The crystal structure of the gallium oxynitride was a highly disordered 2H wurtzite-type with some 3C zinc blende-type stacking faults. The crystals grew in their basal plane changing their aspect ratio with the supplying method of small amounts of Ni or Co and an amount of residual carbon. The acicular crystals were grown by the catalytic behavior of Ni or Co to enhance one-dimensional growth in the hexagonal c-plane.

ダブルペロブスカイト型マンガン酸化物BaYMn2O5+δの酸素貯蔵能
本橋 輝樹, 上田 拓, 鱒渕 友治
燃料電池, 10, 1, 145, 148, 燃料電池開発情報センター, 2010年, ［査読有り］, ［国内誌］
日本語

Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum based Compound Prepared through Citrate Route
Yuji Masubuchi, Shinichi Yamamoto, Takashi Takeda, Shinichi Kikkawa
MULTISCALE, MULTIFUNCTIONAL AND FUNCTIONALLY GRADED MATERIALS, 631-632, 167, +, TRANS TECH PUBLICATIONS LTD, 2010年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（国際会議プロシーディングス）, The oxynitrides with composition A(1-x)B(x)(OyNz) (A: Nb and Ta, B: Al) were studied in preparation through citrate route and NH3 nitridation. In the case of Nb, the product of x = 0.5 prepared at 1000 degrees C was a new compound of a = 0.435 nm with rock salt structure. In this structure, Al and Nb atoms were distributed randomly in the cation sites. Anion sites were also randomly occupied by oxide and nitride ions with some amount of vacancy. The chemical composition was represented as Nb0.56Al0.44O0.38N0.37 square(0.25) from Rietveld refinement and oxygen/nitrogen measurement. In the case of Ta, monoclinic Ta3N5 crystallized with a small amount of Ta4N5 impurity at x = 0.5. Aluminum compound was co-present as amorphous impurity.

高原子価金属酸化物Li_xCoO_2およびCoO_2の電気化学合成とその電子構造(<シリーズ>化学からみた物性物理)
本橋 輝樹, 鱒渕 友治, 吉川 信一, 菅野 了次, Karppinen Maarit, 山内 尚雄
物性研究, 93, 3, 234, 246, 物性研究刊行会, 2009年12月05日, ［査読有り］, ［国内誌］
日本語, この論文は国立情報学研究所の電子図書館事業により電子化されました。

Preparation of Eu-doped beta- and 15R-SiAlONs by ammonia nitridation of the precursor obtained using aluminum glycine gel
Yuji Masubuchi, Mitsue Yoshikawa, Takashi Takeda, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 487, 1-2, 409, 412, ELSEVIER SCIENCE SA, 2009年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Synthesis of Eu-doped beta- and 15R-SiAlONs was studied by the ammonia nitridation of precursors derived from an alpha-Si(3)N(4) fine powder dispersed in aluminum glycine gel with various Si/Al ratio and post-annealing in a nitrogen pressure furnace. The largest amount of beta-SiAlON was observed in the product at 1750 degrees C for Si/Al = 1/1 with small amounts of both alpha- and 15R-SiAlON impurities. The product showed two emissions at around 420 nm and 560 mm. The emission intensities decreased with increasing amount of beta-SiAlON. The former and latter emissions were assigned to Eu(2+) in the 15R- and alpha-SiAlONs impurities. A mixture of Eu-doped 15R-SiAlON with alpha-Al(2)O(3) impurity was obtained for Si/Al = 1/6, using AlN together with Al(NO(3))(3)center dot 9H(2)O in a 2/1 atomic ratio as the aluminum source. It showed a bluish-white emission at 450 rum under 254 nm radiation. (C) 2009 Elsevier B.V. All rights reserved.

Electronic phase diagram of the layered cobalt oxide system LixCoO2 (0.0 ≤ x ≤ 1.0)
Motohashi T, Ono T, Sugimoto Y, Masubuchi Y, Kikkawa S, Kanno R, Karppinen M, Yamauchi H
Physical Review B, 80, 16, 165114, American Physical Society, 2009年10月09日, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Here we report the magnetic properties of the layered cobalt oxide system, LixCoO2, in the whole range of Li composition, 0 ≤ x ≤ 1. Based on dc-magnetic-susceptibility data, combined with results of Co-59 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) observations, the electronic phase diagram of LixCoO2 has been established. As in the related material NaxCoO2, a magnetic critical point is found to exist between x=0.35 and 0.40, which separates the Pauli-paramagnetic and Curie-Weiss metals. In the Pauli-paramagnetic regime (x ≤ 0.35), the antiferromagnetic spin cor...

Structural phase transition in the perovskite-type tantalum oxynitrides, Ca1−Eu Ta(O,N)3
Teruki Motohashi, Yohei Hamade, Yuji Masubuchi, Takashi Takeda, Kei-ichiro Murai, Akira Yoshiasa, Shinich Kikkawa
Materials Research Bulletin, 44, 9, 1899, 1905, Elsevier BV, 2009年09月, ［査読有り］
英語, 研究論文（学術雑誌）

Preparation of gallium oxynitride in the presence of iron through a citrate route
Shinichi Yamamoto, Shinichi Kikkawa, Yuji Masubuchi, Takashi Takeda, Maki Okube, Akira Yoshiasa, Marck Lumey, Richard Dronskowski
MATERIALS RESEARCH BULLETIN, 44, 8, 1656, 1659, PERGAMON-ELSEVIER SCIENCE LTD, 2009年08月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Gallium oxynitrides were prepared in the copresence of various amounts of Fe3+ by ammonia nitridation of oxide precursors. Their crystallinity reduced in a compositional range up to 3 mol% and improved again above 4 mol% with an appearance of a nitride impurity. The product with 2 mol% of Fe3+ showed the maximum oxygen content of 21 mol% and minimum nitrogen content of 24 mol%. X-ray absorption spectroscopy, Mossbauer and magnetic measurements suggested a small amount of Fe3O4-like clusters in the oxynitride products. Density-functional calculations supported that the Fe-O-clustered system is more preferable than the statistical distribution of iron in the hexagonal gallium oxynitride structure. (C) 2009 Elsevier Ltd. All rights reserved.

Niobium-aluminum oxynitride prepared by ammonolysis of oxide precursor obtained through the citrate route
Shinichi Yamamoto, Yoshio Ohashi, Yuji Masubuchi, Takashi Takeda, Teruki Motohashi, Shinichi Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 482, 1-2, 160, 163, ELSEVIER SCIENCE SA, 2009年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Oxynitrides in the (Nb1-xAlx)(O,N) quaternary system were prepared by ammonolysis of oxide precursor obtained through the citrate route. The products at 1000 degrees C were a mixture of Nb(N,O) and NbN0.95 at the niobium end (x = 0) and amorphous Al(O,N) at the aluminum end (x = 1). A new cubic compound (A) appeared mixed with Nb(N,O) in the compositional range 0.1 <= x <= 0.4. Its almost pure product was obtained at x = 0.5. The X- ray diffraction pattern was rock salt type (Nb0.56Al0.44)(O0.38N0.37 square(025)) in Fm-3m with a = 0.43481 (1) nm. The product showed superconductivity with T-c = 15 K. Its crystallinity was much improved and its superconducting volume fraction increased to 32% after its thermal annealing at 1100 degrees C in evacuated sealed tube. A second cubic compound (B), rock salt type Nb[ (O.N)(0.85)square(0.15)] with a = 0.434 nm, was observed mixed with amorphous Al(O,N) in the as-prepared products of the range 0.6 <= x <= 0.9. (c) 2009 Elsevier B.V. All rights reserved.

Magnetoplumbite and W-type barium ferrites as magnetic mixture with hematite
Yuji Masubuchi, Ryoji Saito, Shinichi Kikkawa
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, 117, 1361, 82, 84, CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI, 2009年01月, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
英語, 研究論文（学術雑誌）, Magnetic properties were studied on polycrystalline composite mixtures of magnetoplumbite-type BaFe12O19 and W-type BaCo2Fe16O27 ferrites with alpha-Fe2O3. The respective ferrite mixtures were prepared with hematite in 0 to 70 mol% using solid state reaction. X-ray diffraction (XRD) analysis and magnetic measurement suggested the products were simple mixtures of the ferromagnetic BaFe12O19 or BaCo2Fe16O27 with alpha-Fe2O3 even after sintering at 1250 degrees C. Their magnetization decreased with the increasing contents of alpha-Fe2O3. Their electrical resistivities of higher than 10(2) Omega m were too large to observe their magnetic field dependence, magnetoresistance (MR) effect. Electrical resistivity decreased to 0.36 Omega m by the post annealing of the as prepared BaCo2Fe16O27 with a small amount of alpha-Fe2O3 in Ar at 1000 degrees C for 5 h. The improved electrical conductivity in 4 orders of magnitude showed the MR effect of 0.86% on the post annealed BaCo2Fe16O27 product. (C)2009 The Ceramic society of Japan. All rights reserved.

低温窒化法で合成した巨大磁化Fe₁₆N₂の磁気特性
山下祥平, 鱒渕友治, 吉川信一, 小山佳一
東北大学金属材料研究所強磁場超伝導材料研究センター年次報告, 2008, 2009年

Iron source effect on BaFe12O19 preparation through citrate route
Shinichi Kikkawa, Kentaro Aiba, Yuji Masubuchi, Isao Saeki
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, 117, 1361, 15, 17, CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI, 2009年01月, ［査読有り］, ［国内誌］
英語, 研究論文（学術雑誌）, Both magnetization and coercivity should be controlled on BaFe12O19 for its usage in magnetic recording. Preparation of BaFe12O19 was studied in citrate route by changing the kinds of iron source. Stoichiometric mixtures of iron compounds with Ba(NO3)(2) were dissolved in distilled water. They were mixed with citric acid aqueous solution and then condensed of a hot plate to their gelatinous products. Their prefired products below 450 degrees C were pelletized and then fired in a temperature range between 750 and 900 degrees C. The product from iron nitrate was a mixture of alpha-Fe2O3, BaFe2O4 and a small amount of BaFe12O19. The from Fe(acac)(3) was pure BaFe12O19 fine powder with a crystallite size of < 90 nm. The fine powdered product at 850 degrees C had a saturation magnetization of 58.5 emu.g(-1) and a coercivity of 5.5 kOe. (C)2009 The Ceramic society of Japan. All rights reserved.

Fine Fe16N2 powder prepared by low-temperature nitridation
Shinichi Kikkawa, Atushi Yamada, Yuji Masubuchi, Takashi Takeda
MATERIALS RESEARCH BULLETIN, 43, 12, 3352, 3357, PERGAMON-ELSEVIER SCIENCE LTD, 2008年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, alpha-Fe was prepared by reduction of a fine gamma-Fe2O3 powder under hydrogen at 500 degrees C for 8 h. The alpha-Fe fine powder, about 100 nm in crystallite size, was then nitrided under an ammonia flow at 130 degrees C for 100 h. X-ray single-phase Fe16N2 was obtained with a magnetization value of 225 emu/g at room temperature under a magnetic field of 15 kOe. The Mossbauer spectrum at room temperature could be resolved into three sets of hyperfine fields with an average magnetic moment of 2.52 mu(B). An additional paramagnetic component was present in the spectrum with an area ratio of 19%. (c) 2008 Elsevier Ltd. All rights reserved.

Chemical synthesis, structural elucidation and quantum-chemical modeling of a Cr3+ doped gallium oxynitride prepared by precursor nitridation
Shinichi Yamamoto, Shinichi Kikkawa, Yuji Masubuchi, Takashi Takeda, Holger Wolff, Richard Dronskowski, Akira Yoshiasa
SOLID STATE COMMUNICATIONS, 147, 1-2, 41, 45, PERGAMON-ELSEVIER SCIENCE LTD, 2008年07月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌）, Chromium doped gallium oxynitrides having the wurtzite structure were prepared by ammonia nitridation of oxide precursors derived via the citrate route. The solid solution limits of less than 1 at.% Cr3+ were confirmed by both XRD and EXAFS on the nitrided product at 750 degrees C in the wurtzite-type crystal lattice. The doped product was paramagnetic with a small amount of an antiferromagnetic impurity, but there was no ferromagnetic interaction among the doped Cr3+ ions in the gallium oxynitride. Density-functional electronic Structure calculations on the basis of a wurtzite-type supercell containing 194atoms reveal the oxynitride material to be metastable, and confirm the presence of spin-polarized Cr3+ cations located exactly on former Ga3+ tetrahedral sites. (C) 2008 Elsevier Ltd. All rights reserved.

Preparation of apatite-type La-9.33(SiO4)(6)O(2)oxide ion conductor by alcoxide-hydrolysis
Y Masubuchi, M Higuchi, T Takeda, S Kikkawa
JOURNAL OF ALLOYS AND COMPOUNDS, 408, 641, 644, ELSEVIER SCIENCE SA, 2006年02月, ［査読有り］, ［筆頭著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Both powder and film of apatite-type La-9.33(SiO4)(6)O-2 were prepared by alcoxide-hydrolysis. The apatite formation temperature was considerably lowered in this preparation method comparing to its solid-state reaction. Its sintered body did not show any particular orientation of the anisotropic apatite crystals. Electrical conductivity was 7.2 x 10(-5) S cm(-1) at 500 degrees C. The films deposited on quartz glass and Pt substrates with thickness of either 1.0 or 1.5 mu m had uniform microstructure extended on their surface. Preferred orientation of La-9.33(SiO4)(6)O-2 was observed on the surface of the film deposited on quartz glass substrate; its basal plane was parallel to the substrate. (c) 2005 Published by Elsevier B.V.

Oxide ion conduction mechanism in RE9.33(SiO4)(6)O-2 and Sr2RE8(SiO4)(6)O-2 (RE=La, Nd) from neutron powder diffraction
Y Masubuchi, M Higuchi, T Takeda, S Kikkawa
SOLID STATE IONICS, 177, 3-4, 263, 268, ELSEVIER SCIENCE BV, 2006年01月, ［査読有り］, ［筆頭著者］, ［国際誌］
英語, 研究論文（学術雑誌）, The oxide ion conduction mechanism was clarified for high purity RE9.33(SiO4)(6)O-2 and Sr2RE8(SiO4)(6)O-2 (RE= La and Nd) by Rietveld and maximum entropy method (MEM) analysis using neutron powder diffraction data collected at room temperature. All the compounds had an apatite-type structure in the space group P6(3)/m. Neither site splitting nor interstitial sites of the oxide ion was observed. RE9.33(SiO4)(6)O-2 had cation vacancies only at the 4f site. In Sr2RE8(SiO4)(6)O-2, the 4f sites were fully occupied by strontium and rare earths with a molar ratio of 1:1. Also, in RE9.33(SiO4)(6)O-2, the oxide ion at the hexagonal channel site had a large displacement along the c-axis. This large displacement is induced by cooperative rotation Of SiO4 tetrahedra around rare earths at the 4f site through oxide ion polyhedra around another rare earth at the 6h site. The displacement, enhanced by a vacancy in the 4f site, is directly related to oxide ion conduction in RE9.33(SiO4)(6)O-2. (c) 2005 Elsevier B.V. All rights reserved.

Structure of oxide ion-conducting lanthanum oxyapatite, La 9.33(SiO4)6O2
Hiroki Okudera, Yuuji Masubuchi, Shinichi Kikkawa, Akira Yoshiasa
Solid State Ionics, 176, 15-16, 1473, 1478, ELSEVIER SCIENCE BV, 2005年05月12日, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Crystallographic space group and structural parameters of oxide ion conductor La9.33(SiO4)6O2 were investigated based on single-crystal X-ray diffraction data at room temperature (296 K). Results of structure refinements with various structure models indicated that the subjected compound has an apatite structure (space group P63/m) with no symmetry lowering and site splitting. The structure refinement was converged at R, wR, and S of 0.018, 0.026, and 0.90, respectively, with 41 parameters. Thermal displacements of the oxide ion at the hexagonal channel site (at 0,0,1/4) were extremely large along the c-axis direction. Seven-coordinated cation sites (6h La site) were basically fully occupied and cation vacancies were found at the nine-coordinated 4f La site. These results showed good coincidence with the compound's high oxide ion conductivity. Crystallographic data at 296 K: cell dimensions a = 9.714(1) Å and c = 7.183(2) Å
F(000) = 824
Z = 1
Dc = 5.464(2) g cm-3. © 2005 Elsevier B.V. All rights reserved.

アパタイト型酸素イオン伝導体における導電機構　　　　　　　　　　　　　　　
鱒渕友治, 武田隆史, 吉川信一
化学, 60, 66, 67, 2005年, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
日本語, 研究論文（その他学術会議資料等）

Temperature dependence of structural parameters in oxide-ion-conducting Nd-9.33(SiO4)(6)O-2: single crystal X-ray studies from 295 to 900 K
H Okudera, A Yoshiasa, Y Masubuchi, M Higuchi, S Kikkawa
JOURNAL OF SOLID STATE CHEMISTRY, 177, 12, 4451, 4458, ACADEMIC PRESS INC ELSEVIER SCIENCE, 2004年12月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Crystallographic space group, structural parameters and their thermal changes in oxide-ion-conducting Nd-9.33(SiO4)(6)O-2 were investigated using high-temperature single-crystal X-ray diffraction experiments in the temperature range of 295 less than or equal to T less than or equal to 900 K. The title compound has the apatite structure (space group P6(3)/m), and no notable structural change occurred over the temperature range examined. Observed anisotropy in thermal motions of oxide ions which belong to SiO4 tetrahedron indicated high rigidity of the tetrahedron in the structure, indicating that they form sp3 hybrid orbitals and the ligand oxygens do not take part in oxide-ion conductivity. Virtually full occupation of the 6h Nd site and highly anisotropic displacements of oxide ion inside the hexagonal channel were maintained over the temperature range examined. This result confirms that oxide-ion transport inside the hexagonal channel is the dominant process of conduction in the title compound. (C) 2004 Elsevier Inc. All rights reserved.

Single crystal growth and oxide ion conductivity of oxyapatite type Sr-bearing neodymium silicate
Y Masubuchi, M Higuchi, S Kikkawa, K Kodaira, S Nakayama
SOLID STATE IONICS, 175, 1-4, 357, 360, ELSEVIER SCIENCE BV, 2004年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Single crystals of Sr-bearing neodymium silicates with the oxyapatite structure were grown by the floating zone method. The grown crystals were free from any macroscopic defects and their quality was sufficient for electrical measurements. Electrical conductivity was enhanced by about three orders of magnitude by the introduction of cation vacancies to Sr2Nd8(SiO4)(6)O-2, a compound without cation or oxygen ion vacancies. The introduction of oxygen ion vacancies to Sr2Nd8(SiO4)(6)O-2 and Nd-9.33(SiO4)(6)O-2 did not significantly affect their electrical conductivity. Cation vacancies may play an important role for oxygen ion conduction in oxyapatite type rare-earth silicates. (C) 2004 Elsevier B.V. All rights reserved.

Single crystal growth and oxide ion conductivity of apatite-type rare-earth silicates
M Higuchi, Y Masubuchi, S Nakayama, S Kikkawa, K Kodaira
SOLID STATE IONICS, 174, 1-4, 73, 80, ELSEVIER SCIENCE BV, 2004年10月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, Rare-earth silicate with an apatite structure is a new type of oxide ion conductor, the electrical conductivity of which is higher at relatively low temperatures than that of stabilized zirconia. Single crystals are indispensable in order to reveal the intrinsic bulk properties such as anisotropy of electrical conductivity. This paper reviews our recent research work on single crystals growth by the floating zone method and electrical properties of this material, including reinvestigation of phase relations in Nd2O3-SiO2 system and structure refinement using neutron diffraction. A possible mechanism for the oxide ion conduction is proposed based on the existence of cation vacancies. (C) 2004 Elsevier B.V. All rights reserved.

アルコキシド加水分解法によるアパタイト型酸素イオン導電体La9.33(SiO4)6O2の合成　　　　　　　　　　　　　　　
Y. Masubuchi, M. Higuchi, T. Takeda, S. Kikkawa
Proceedings of the 15th Symposium on Functionally Graded Materials, 321, 326, 2004年, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
日本語, 研究論文（国際会議プロシーディングス）

Determinations of crystallographic space group and atomic arrangements in oxide-ion-conducting Nd-9.33(SiO4)(6)O-2
H Okudera, A Yoshiasa, Y Masubuchi, M Higuchi, S Kikkawa
ZEITSCHRIFT FUR KRISTALLOGRAPHIE, 219, 1, 27, 31, R OLDENBOURG VERLAG, 2004年, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）, In this paper we report single crystal X-ray diffraction study of an oxide-ion-conductor Nd-9.33(SiO4)(6)O-2 at 150 K. By detailed examinations of the atomic positions and an electron density distribution, it was clearly shown that Nd-9.33(SiO4)(6)O-2 has an apatite structure (space group P6(3)/m) with no symmetry lowering or site-splitting. All oxygens in the hexagonal channel were located at their ideal positions (2a site at 0, 0, (1)/(4)) of the apatite structure, while their thermal displacements were highly anisotropic and that in the c-axis direction was more than four-times larger than those in other directions. Cation vacancies were located at the nine-coordinated 4f Nd site. The other Nd site (seven-coordinated 6h site) were basically fully occupied. This full occupation of the 6h Nd site makes potential waves inside the hexagonal channel smooth and transports of oxide-ions in the channel much easier. The distortion Of SiO4 tetrahedron was not apparent. Crystallographic data at 150 K: Cell dimensions a = 9.5556(6) Angstrom and c = 7.019(2) Angstrom; F-(000) = 852; Z = 1; D-c = 5.779(2) g/cm(3).

Oxide ion conduction in Nd-9.33(SiO4)(6)O-2 and Sr2Nd8(SiO4)(6)O-2 single crystals grown by floating zone method
Y Masubuchi, M Higuchi, H Katase, T Takeda, S Kikkawa, K Kodaira, S Nakayama
SOLID STATE IONICS, 166, 1-2, 213, 217, ELSEVIER SCIENCE BV, 2004年01月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Single crystals of Nd-9.33(SiO4)(6)O-2 and Sr2Nd8(SiO4)(6)O-2 oxide ion conductors with the oxyapatite structure were grown without any macroscopic defect by the floating zone method. The oxide ion conductivity of the Sr2Nd8(SiO4)(6)O-2 single crystal varied with the distance from its seed crystal along the growth direction, because of its changing deficiency in Sr content. Its stoichiometric portion had a lower electrical conductivity by about five orders of magnitude at 600 degreesC than the value for Nd-9.33(SiO4)(6)O-2 single crystal. Structural refinement of neutron diffraction data for powdered Nd-9.33(SiO4)(6)O-2 single crystal showed that the previous structure analysis was misleading. Cation vacancies were present only at 4f site and its channel oxygen site was fully occupied in space group of P6(3)/m. The oxygen had an anisotropic displacement along the channel in the refined oxyapatite structure. (C) 2003 Elsevier B.V. All rights reserved.

Determinations of crystallographic space group and atomic arrangements in oxide-ion-conducting Nd9.33(SiO4)6O2
Hiroki Okudera, Akira Yoshiasa, Yuji Masubuchi, Mikio Higuchi, Shinichi Kikkawa
Zeitschrift für Kristallographie - Crystalline Materials, 219, 1, 27, 31, Walter de Gruyter GmbH, 2004年01月01日
Abstract
In this paper we report single crystal X-ray diffraction study of an oxide-ion-conductor Nd9.33(SiO4)6O2 at 150 K. By detailed examinations of the atomic positions and an electron density distribution, it was clearly shown that Nd9.33(SiO4)6O2 has an apatite structure (space group P63/m) with no symmetry lowering or site-splitting. All oxygens in the hexagonal channel were located at their ideal positions (2a site at 0, 0, ¼) of the apatite structure, while their thermal displacements were highly anisotropic and that in the c-axis direction was more than four-times larger than those in other directions. Cation vacancies were located at the nine-coordinated 4f Nd site. The other Nd site (seven-coordinated 6h site) were basically fully occupied. This full occupation of the 6h Nd site makes potential waves inside the hexagonal channel smooth and transports of oxide-ions in the channel much easier. The distortion of SiO4 tetrahedron was not apparent. Crystallographic data at 150 K: Cell dimensions a = 9.5556(6) Å and c = 7.019(2) Å; F
(000) = 852; Z = 1; D
c = 5.779(2) g/cm3.

Reinvestigation of phase relations around the oxyapatite phase in the Nd2O3-SiO2 system
Y Masubuchi, M Higuchi, K Kodaira
JOURNAL OF CRYSTAL GROWTH, 247, 1-2, 207, 212, ELSEVIER SCIENCE BV, 2003年01月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際誌］
英語, 研究論文（学術雑誌）, Phase relations around the oxyapatite phase in the Nd2O3-SiO2 system have been investigated by means of a slow cooling floating zone (SCFZ) method and solid-state reactions. The results on SCFZ proved that the oxyapatite phase melts congruently at the composition of Nd2O3:SiO2=7:9, corresponding to Nd-9.33(SiO4)(6)O-2. The 2:3 phase (Nd-8(SiO4)(6)), which had been believed to have an apatite structure and to melt congruently, does not exist and consists of a mixture of Nd-9.33(SiO4)(6)O-2 and Nd2Si2O7 Phases. The solid-state reaction revealed that a solid solution region of the oxyapatite phase is extremely narrow or does not exist below 1650 degreesC. (C) 2002 Elsevier Science B.V, All rights reserved.

Nd_2O_3-SiO_2系におけるアパタイト相近傍の相関係 : バイオII
樋口 幹雄, 鱒渕 友治, 小平 紘平
日本結晶成長学会誌, 27, 1, 120, 120, 日本結晶成長学会, 2000年07月01日, ［査読有り］, ［国内誌］
日本語, Phase relations around the apatite phase in the Nd_2O_3-SiO_2 system have been reinvestigated by the slow-cooling floating zone technique and conventional solid state reactions. Nd_3(SiO_4)_6 believed to have an apatite structure and to melt congruently does not exist as a pure phase, whereas Nd_<9.33>(SiO_4)O_2 having an apatite structure is found to melt congruently. Solid solubility of the apatite phase is also discussed.

金属カルボジイミド化合物の特異な熱膨張　　　　　　　　　　　　　　　
鱒渕友治, 若林紅音, 樋口幹雄
日本セラミックス協会年会講演予稿集(Web), 2022年
2022年 - 2022年

窒素含有フラックスを用いたペロブスカイト型酸窒化物微結晶の合成　　　　　　　　　　　　　　　
鱒渕友治
日本セラミックス協会秋季シンポジウム講演予稿集(Web), 2021年
2021年 - 2021年

新規カルボジイミドBa_0.9Sr_0.1CN₂の圧力相転移と蛍光体への応用　　　　　　　　　　　　　　　
鱒渕友治, 宮崎涼花, 樋口幹雄
日本セラミックス協会年会講演予稿集(Web), 2021年
2021年 - 2021年

GdVO₄:Eu単結晶の育成とそのベータ線シンチレーション特性　　　　　　　　　　　　　　　
樋口幹雄, 松岡みのり, 錦戸文彦, 山谷泰賀, 武田隆史, 鱒渕友治, 金子純一
日本セラミックス協会秋季シンポジウム講演予稿集(Web), 2021年
2021年 - 2021年

BaCN₂を用いたペロブスカイト型酸窒化物BaTaO₂Nの合成と微細構造　　　　　　　　　　　　　　　
小山恭平, 鱒渕友治, 樋口幹雄
日本セラミックス協会秋季シンポジウム講演予稿集(Web), 2021年
2021年 - 2021年

Li₂CaSiO₄:Euの合成とその発光特性　　　　　　　　　　　　　　　
張楚明, 樋口幹雄, 鱒渕友治, 金子純一
セラミックス基礎科学討論会講演要旨集, 2021年
2021年 - 2021年

構造相転移を有する(Ba_0.9Sr_0.1)CN₂:Eu²⁺蛍光体　　　　　　　　　　　　　　　
宮崎涼花, 鱒渕友治, 樋口幹雄
セラミックス基礎科学討論会講演要旨集, 2021年
2021年 - 2021年

ホウ素系助剤を用いたペロブスカイト型酸窒化物SrTaO₂Nの焼結とEPD法による高密度厚膜焼結体の作製　　　　　　　　　　　　　　　
宮本大生, 鱒渕友治, 樋口幹雄, 石井健斗, 打越哲郎
セラミックス基礎科学討論会講演要旨集, 2021年
2021年 - 2021年

溶媒移動浮遊帯溶融法によるYb:CaGdAl₃O₇単結晶の育成　　　　　　　　　　　　　　　
樋口幹雄, 樋口幹雄, 藤井源, 鱒渕友治, 小川貴代, 和田智之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2020年
2020年 - 2020年

ペロブスカイト型酸窒化物強誘電体BaTaO₂N微結晶の作製　　　　　　　　　　　　　　　
細野新, 鱒渕友治, 安井伸太郎, 武貞正樹, 樋口幹雄, 伊藤満, 吉川信一
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2020年
2020年 - 2020年

強誘電体微結晶BaTaO₂Nペロブスカイトの合成　　　　　　　　　　　　　　　
鱒渕友治, 細野新, 樋口幹雄, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2020年
2020年 - 2020年

固体窒素源を用いたSr-Ta系酸化物前駆体薄膜の窒化　　　　　　　　　　　　　　　
樋口亜門, ROSERO-NAVARRO Nataly Calorina, 三浦章, 鱒渕友治, 忠永清治
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2020年
2020年 - 2020年

新規カルボジイミド(Ba_0.9Sr_0.1)CN₂の合成と結晶構造　　　　　　　　　　　　　　　
宮崎涼花, 鱒渕友治, 樋口幹雄
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2020年
2020年 - 2020年

SrCO₃及びB₂O₃を助剤としたペロブスカイト型酸窒化物SrTaO₂Nの均一焼結　　　　　　　　　　　　　　　
宮本大生, 鱒渕友治, 樋口幹雄
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2020年
2020年 - 2020年

浮遊帯溶融法によるGdVO₄:Eu単結晶の育成とベータ線イメージングへの応用　　　　　　　　　　　　　　　
松岡みのり, 樋口幹雄, 鱒渕友治, 錦戸文彦, 山谷泰賀, 武田隆史, 金子純一
結晶成長国内会議予稿集(CD-ROM), 2020年
2020年 - 2020年

固体窒素源を用いた酸窒化物の低温合成　　　　　　　　　　　　　　　
鱒渕友治, 定尚輝, YANG Q., 樋口幹雄
日本セラミックス協会年会講演予稿集(CD-ROM), 2020年
2020年 - 2020年

種々の固体窒素源を用いたSr-Ta系酸窒化物の合成　　　　　　　　　　　　　　　
木下祐輝, 岡田凌輝, 樽谷直紀, 片桐清文, 犬丸啓, 小山恭平, 鱒渕友治
日本セラミックス協会年会講演予稿集(CD-ROM), 2020年
2020年 - 2020年

BaCN₂を用いたBa-Si酸窒化物蛍光体の低温合成と反応メカニズムの解明　　　　　　　　　　　　　　　
定尚輝, 鱒渕友治, 河原由輝, 新井健司, 本橋輝樹, 樋口幹雄
セラミックス基礎科学討論会講演要旨集, 2020年
2020年 - 2020年

REドープホウ酸塩の合成とその中性子イメージングへの応用(RE=Eu,Tb)　　　　　　　　　　　　　　　
仲西亮太, 樋口幹雄, 樋口幹雄, 鱒渕友治, 竹谷篤, 高梨宇宙, 後藤誠, 大竹淑恵
セラミックス基礎科学討論会講演要旨集, 2020年
2020年 - 2020年

メリライト型Ybドープ酸化物の分光学的性質と結晶育成　　　　　　　　　　　　　　　
樋口幹雄, 樋口幹雄, 近添慎弥, 小川貴代, 和田智之, 鱒渕友治
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

ペロブスカイト型酸窒化物誘電体の緻密化　　　　　　　　　　　　　　　
大瀧壮太, 鱒渕友治, 樋口幹雄, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2019年
2019年 - 2019年

酸化物の還元反応を用いたSm₂Fe₁₇N_x磁性体の合成　　　　　　　　　　　　　　　
内田健太, 鱒渕友治, 樋口幹雄, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2019年
2019年 - 2019年

Eu²⁺イオンの5d-4f発光エネルギーの圧力依存性と体積弾性率との相関　　　　　　　　　　　　　　　
HUA H., 上田純平, 鱒渕友治, 田部勢津久
ガラスおよびフォトニクス材料討論会講演要旨集, 2019年
2019年 - 2019年

BaCN₂融液中におけるペロブスカイト型BaTaO₂N微結晶の成長　　　　　　　　　　　　　　　
細野新, 鱒渕友治, 樋口幹雄, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

種々の固体窒素源を用いたGaN:ZnOの合成とキャラクタリゼーション　　　　　　　　　　　　　　　
藤井侑樹, 林優樹, 片桐清文, 犬丸啓, 鱒渕友治, 木下誠志, 野田泰斗, 三好亮暢, 前田和彦
日本セラミックス協会年会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

赤色蛍光体BaCN²:Eu²⁺における発光の温度依存性と残光特性　　　　　　　　　　　　　　　
西谷沙耶香, 鱒渕友治, 樋口幹雄
日本セラミックス協会年会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

種々の固体窒素源によるGaN:ZnOの合成と⁷¹Ga固体NMR法による解析　　　　　　　　　　　　　　　
藤井侑樹, 林優樹, 片桐清文, 犬丸啓, 鱒渕友治, 木下誠志, 野田泰斗, 三好亮暢, 前田和彦
日本ゾル-ゲル学会討論会講演予稿集, 2019年
2019年 - 2019年

固体窒素源を用いた機能性酸窒化物の合成と結晶成長　　　　　　　　　　　　　　　
鱒渕友治, 細野新, 只木幹也, 吉川信一
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2018年
2018年 - 2018年

TiO₂-Ga₂O₃-Bi₂O₃系化合物の合成と結晶構造解析および特性評価　　　　　　　　　　　　　　　
八木亮太, 山根久典, 鱒渕友治
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2018年
2018年 - 2018年

窒化チタンナノ粒子が分散析出したSi(O,N)アモルファス粉体の作製とその光化学特性　　　　　　　　　　　　　　　
佐川祐輝, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2018年
2018年 - 2018年

ペロブスカイト型酸窒化物固溶体Sr_1-xLa_xTa_1-xTi_xO₂Nの焼結と誘電特性　　　　　　　　　　　　　　　
大瀧壮太, 鱒渕友治, 樋口幹雄, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2018年
2018年 - 2018年

ストロンチウムを過剰に含むSrTaO₂N酸窒化物ペロブスカイトの結晶構造と性質　　　　　　　　　　　　　　　
末本祐也, 鱒渕友治, 永峰佑起, 松谷淳生, 芝原豪, 山崎久美子, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2018年
2018年 - 2018年

浮遊帯溶融法によるYbドープK₂NiF₄型およびメリライト型酸化物単結晶の育成　　　　　　　　　　　　　　　
近添慎弥, 樋口幹雄, 樋口幹雄, 小川貴代, 和田智之, 緑川克美, 鱒渕友治, 三浦章, 忠永清治
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2018年
2018年 - 2018年

チタン酸カリウムK₂TiO₃由来のコロイド溶液を用いたアナターゼ型Ti_1-xTa_x(O,N)₂光触媒の合成　　　　　　　　　　　　　　　
大科史典, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2018年
2018年 - 2018年

新規赤色蛍光体BaCN₂:Eu²⁺の発光特性とその温度依存性　　　　　　　　　　　　　　　
西谷沙耶香, 鱒渕友治, 樋口幹雄, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2018年
2018年 - 2018年

メリライト型Ybドープ酸化物の分光学的性質と単結晶育成　　　　　　　　　　　　　　　
近添慎弥, 樋口幹雄, 樋口幹雄, 小川貴代, 和田智之, 緑川克美, 鱒渕友治
結晶成長国内会議予稿集(CD-ROM), 2018年
2018年 - 2018年

BaCN₂融液を用いたペロブスカイト型BaTaO₂N結晶の合成　　　　　　　　　　　　　　　
細野新, 鱒渕友治, 樋口幹雄, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2018年
2018年 - 2018年

尿素を窒素源とするZn-Ga層状複水酸化物からGaN:ZnOへの転換反応のメカニズムの解明　　　　　　　　　　　　　　　
林優樹, 片桐清文, 犬丸啓, 前田和彦, 山本梨乃, 川上望美, 内山智貴, 内本喜晴, 定尚樹, 大瀧壮太, 鱒渕友治
日本セラミックス協会年会講演予稿集(CD-ROM), 2018年
2018年 - 2018年

尿素を用いたLa₂Ti₂O₇からLaTiO₂Nへの窒化反応のメカニズムの解析　　　　　　　　　　　　　　　
岡田凌輝, 片桐清文, 犬丸啓, 定尚樹, 大瀧壮太, 鱒渕友治
日本セラミックス協会年会講演予稿集(CD-ROM), 2018年
2018年 - 2018年

酸窒化物ペロブスカイトBaTaO₂Nの熱安定性と焼結体の誘電性　　　　　　　　　　　　　　　
細野新, 鱒渕友治, 吉川信一, 永峰佑起, 芝原豪
日本セラミックス協会年会講演予稿集(CD-ROM), 2017年
2017年 - 2017年

非晶質酸窒化物薄膜からの窒化物ナノ粒子の析出挙動　　　　　　　　　　　　　　　
鱒渕友治, 宮本優子, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2017年
2017年 - 2017年

FePtをコアとした“α”-Fe₁₆N₂”被覆複合粒子の微細構造と磁性　　　　　　　　　　　　　　　
山内亮二, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2017年
2017年 - 2017年

窒化炭素C₃N₄を窒素源とする酸窒化物SrTaO₂Nの合成とその反応機構　　　　　　　　　　　　　　　
只木幹也, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2017年
2017年 - 2017年

岩塩型酸窒化ニオブの超伝導特性への格子欠陥導入による影響　　　　　　　　　　　　　　　
立野康太, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2017年
2017年 - 2017年

粒界にアルミナが析出した“α”-Fe₁₆N₂”複合粉体の合成と磁気特性　　　　　　　　　　　　　　　
松本喜幸, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2017年
2017年 - 2017年

ブラウンミラーライト型Ca₂AlMnO_5+δの酸素吸収速度に対するGa置換効果　　　　　　　　　　　　　　　
稲吉健, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2016年
2016年 - 2016年

ペロブスカイト型酸窒化物誘電体の熱分解と結晶構造　　　　　　　　　　　　　　　
鱒渕友治, 土生大樹, CHEN D-X., 吉川信一
セラミックス基礎科学討論会講演要旨集, 2016年
2016年 - 2016年

高周波スパッタ析出した(M,Si)酸窒化物薄膜(M=Zr,Nb)とその熱処理による色調変化　　　　　　　　　　　　　　　
宮本優子, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2016年
2016年 - 2016年

窒化炭素C₃N₄を窒素源とするペロブスカイト型酸窒化物SrTaO₂Nの合成　　　　　　　　　　　　　　　
只木幹也, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2016年
2016年 - 2016年

NaNH₂融液を用いたマンガン酸窒化物の合成とその酸素還元触媒能　　　　　　　　　　　　　　　
三浦章, ROSERO-NAVARRO Carolina, 鱒渕友治, 樋口幹雄, 吉川信一, 忠永清治
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2016年
2016年 - 2016年

硬磁性FePtを共存させて合成した“α′′-Fe₁₆N₂“の構造と磁性　　　　　　　　　　　　　　　
山内亮二, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2016年
2016年 - 2016年

低温窒化反応による”α”-Fe₁₆N₂”/FePt硬磁性複合体の合成　　　　　　　　　　　　　　　
鱒渕友治, 山内亮二, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2016年
2016年 - 2016年

ペロブスカイト型酸窒化物La_1-xSr_xTiO_2+xN_1-x(x=0,0.2)の窒化物イオン分布　　　　　　　　　　　　　　　
土生大樹, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2015年
2015年 - 2015年

ダブルペロブスカイト型BaLaMn₂O_5+δを用いた水分解反応による水素生成　　　　　　　　　　　　　　　
本橋輝樹, 木村誠, 鱒渕友治, 吉川信一, GEORGE Janine, DRONSKOWSKI Richard
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2015年
2015年 - 2015年

Zr_1-xSi_x酸窒化物アモルファス薄膜(x=0,0.4,0.5)の熱処理効果と色調変化　　　　　　　　　　　　　　　
宮本優子, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2015年
2015年 - 2015年

ZnGa₂O₄を用いた(Ga,Zn)(N,O)ナノワイヤの合成　　　　　　　　　　　　　　　
鱒渕友治, 香村惇夫, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2015年
2015年 - 2015年

酸窒化ニオブの生成におけるMnおよびSi添加効果　　　　　　　　　　　　　　　
鱒渕友治, 北原悠輝, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2015年
2015年 - 2015年

ZnGa₂O₄からの酸窒化ガリウムナノワイヤの生成　　　　　　　　　　　　　　　
香村惇夫, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2015年
2015年 - 2015年

Additive Sintering, Post-annealing and Dielectric Properties of SrTaO2N
SUN Shi‐Kuan, MASUBUCHI Yuji, MOTOHASHI Teruki, KIKKAWA Shinichi
セラミックス基礎科学討論会講演要旨集, 2014年01月09日, 英語

Coを共存させた鉄窒化物の磁気特性　　　　　　　　　　　　　　　
佐藤大晃, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2014年
2014年 - 2014年

酸窒化ニオブの合成におけるMnおよびNi添加効果　　　　　　　　　　　　　　　
北原悠輝, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会講演予稿集, 2014年
2014年 - 2014年

粒子径を制御したBaFe₁₂O₁₉とそのFe₃O₄複合粉体の合成と磁気特性　　　　　　　　　　　　　　　
津川優太, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2014年
2014年 - 2014年

ダブルペロブスカイト型BaLnMn₂O_5+δ(Ln=Y,Gd,Nd,La)の水からの水素生成反応性　　　　　　　　　　　　　　　
木村誠, 本橋輝樹, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2014年
2014年 - 2014年

分相現象を利用した酸化鉄多孔体の作製　　　　　　　　　　　　　　　
神森大地, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会講演予稿集, 2014年
2014年 - 2014年

ペロブスカイト型酸窒化物誘電体の安定性と高圧成型体の誘電特性　　　　　　　　　　　　　　　
鱒渕友治, 土生大樹, CHEN D., 本橋輝樹, 吉川信一, 谷口尚
日本セラミックス協会年会講演予稿集(CD-ROM), 2014年
2014年 - 2014年

ダブルペロブスカイト型BaYMn₂O_5+δの結晶構造から見た顕著な酸素吸収放出　　　　　　　　　　　　　　　
本橋輝樹, 高橋平, 鱒渕友治, 吉川信一, 久保田佳基, 小林洋治, 陰山洋, 高田昌樹, 高田昌樹, 北川進, 松田亮太郎
日本セラミックス協会年会講演予稿集(CD-ROM), 2014年
2014年 - 2014年

BaFe₁₂O₁₉粒子上へのFe₃O₄の生成とその磁気特性　　　　　　　　　　　　　　　
津川優太, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2014年
2014年 - 2014年

ペロブスカイト型酸窒化物SrTaO₂Nにおける超高圧成型の効果　　　　　　　　　　　　　　　
鱒渕友治, 本橋輝樹, 吉川信一, 谷口尚
セラミックス基礎科学討論会講演要旨集, 2014年
2014年 - 2014年

強磁場コロイドプロセス法によるランタンシリケート配向体の作製
高橋聡志, 小林清, 鈴木達, 鱒渕友治, 目義雄, 石垣隆正, 打越哲郎
電気化学会大会講演要旨集, 2013年03月29日, 日本語

ブラウンミラーライト型Ca₂AlMnO_5+δの酸素吸収挙動に対する温度・雰囲気の影響
本橋輝樹, 平野佑佳, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2013年03月11日, 日本語

酸窒化ガリウム系ナノワイヤ(Ga,M)(O,N)(M=Al,Zn)の形成における遷移金属添加効果
鱒渕友治, 香村惇夫, 山岡諒平, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集(CD-ROM), 2013年03月11日, 日本語

強磁場コロイドプロセス法によるランタンシリケート配向体の作製
高橋聡志, 小林清, 鈴木達, 鱒渕友治, 目義雄, 石垣隆正, 打越哲郎
日本セラミックス協会年会講演予稿集(CD-ROM), 2013年03月11日, 日本語

Fabrication of dielectric SrTaO2N ceramics
SUN Shi‐Kuan, ZHANG Ya‐Ru, MASUBUCHI Yuji, MOTOHASHI Teruki, KIKKAWA Shinichi
日本セラミックス協会年会講演予稿集(CD-ROM), 2013年03月11日, 英語

低温窒化合成した′′α′′‐(Fe,Co)₁₆N₂′′における結晶構造と磁気特性
佐藤大晃, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年01月09日, 日本語

TEOSの加水分解を用いた酸化物および窒化物/シリカ複合体の形成とその組織制御
鱒渕友治, 橋本郁哉, 神森大地, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年01月09日, 日本語

ブラウンミラーライト型Ca₂AlMnO_5+δ(δ=0~0.5)の顕著な酸素吸収放出と結晶構造変化
平野佑佳, 本橋輝樹, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年01月09日, 日本語

高周波スパッタTi‐Si‐(N,O)アモルファス薄膜の雰囲気アニール効果
澤田亮典, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年01月09日, 日本語

TEOSの加水分解を用いた酸化物および窒化物／シリカ複合体の形成とその組織制御　　　　　　　　　　　　　　　
鱒渕友治, 橋本郁也, 神森大地, 本橋輝樹, 吉川信一
第51回セラミックス基礎科学討論会, 2013年01月09日, 日本語, 口頭発表（一般）
［国内会議］

サーモクロミックガラスへの応用を目指したVO₂/SiO₂複合体の作製　　　　　　　　　　　　　　　
橋本郁哉, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2013年
2013年 - 2013年

ダブルペロブスカイト型BaLnMn₂O_5+δ(Ln=La,Nd,Y)の酸素吸収放出特性と還元剤としての反応活性　　　　　　　　　　　　　　　
本橋輝樹, 木村誠, 高橋平, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2013年
2013年 - 2013年

ダブルペロブスカイト型BaYMn₂O_5+δ(0≦δ≦1)の低酸素分圧下における高温結晶構造　　　　　　　　　　　　　　　
高橋平, 本橋輝樹, 鱒渕友治, 吉川信一, 久保田佳基, 小林洋治, 陰山洋, 高田昌樹, 高田昌樹, 北川進, 松田亮太郎
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2013年
2013年 - 2013年

異種元素を添加したα”-Fe₁₆N₂における磁気特性制御　　　　　　　　　　　　　　　
佐藤大晃, 津川優太, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2013年
2013年 - 2013年

高周波スパッタTi-Si-(N,O)アモルファス薄膜の雰囲気アニール効果　　　　　　　　　　　　　　　
澤田亮典, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年
2013年 - 2013年

低温窒化合成した′′α′′-(Fe,Co)₁₆N₂′′における結晶構造と磁気特性　　　　　　　　　　　　　　　
佐藤大晃, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2013年
2013年 - 2013年

強磁場コロイドプロセス法によるランタンシリケート配向体の作製
高橋聡志, 打越哲郎, 小林清, 鈴木達, 目義雄, 鱒渕友治, 石垣隆正
無機マテリアル学会学術講演会講演要旨集, 2012年11月01日, 日本語

新規機能性酸窒化物における機能と結晶構造　　　　　　　　　　　　　　　
鱒渕友治
日本セラミックス協会第25回秋季シンポジウム, 2012年09月19日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］

HEXAGONAL GALLIUM OXYNITRIDE NANOWIRE: ITS STRUCTURE AND OPTICAL PROPERTIES　　　　　　　　　　　　　　　
Yuji Masubuchi, Ryohei Yamaoka, Teruki Motohashi, Shinichi Kikkawa
ISNT 2012, 2012年06月03日, 英語, 口頭発表（一般）
［国際会議］

機能性酸窒化物の創製と機能発現機構の解明　　　　　　　　　　　　　　　
鱒渕友治
日本セラミックス協会2012年 年会, 2012年03月19日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］

鎖状構造を持つK2TiO3の酸性溶液への溶解機構と溶存状態　　　　　　　　　　　　　　　
鱒渕友治, 宮崎涼, 菊地拓希, 本橋輝樹, 吉川信一
第50回セラミックス基礎科学討論会, 2012年01月12日, 日本語, 口頭発表（一般）
［国内会議］

高周波スパッタFe-Si-Oアモルファスのアニールによる磁性グラニュラー薄膜の作製　　　　　　　　　　　　　　　
澤田亮典, 鱒渕友治, 本橋輝樹, 吉川信一, 佐々木正秀
日本セラミックス協会年会講演予稿集, 2012年
2012年 - 2012年

低温アンモニア窒化法で合成した“α”-Fe₁₆N₂”における結晶構造と磁性　　　　　　　　　　　　　　　
山下祥平, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2012年
2012年 - 2012年

可溶性チタン源K₂TiO₃を用いた新規酸窒化物ペロブスカイトRTiO₂N(R=希土類元素)の合成　　　　　　　　　　　　　　　
大橋良央, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2012年
2012年 - 2012年

ダブルペロブスカイト型BaYMn₂O_5+δの酸素吸収放出特性に対する希土類元素置換効果　　　　　　　　　　　　　　　
本橋輝樹, 上田拓, 高橋平, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM), 2012年
2012年 - 2012年

Li-Nb酸窒化物(Li_0.88□_0.12)Nb_3.0(O_0.13N_0.87)₄における超伝導　　　　　　　　　　　　　　　
本橋輝樹, 伊藤正彦, 鱒渕友治, 分島亮, 吉川信一
応用物理学会学術講演会講演予稿集(CD-ROM), 2012年
2012年 - 2012年

ブラウンミラーライト型Ca₂(Al_xMn_1-x)₂O_5+δ(x=0.50~0.67)の酸素貯蔵能　　　　　　　　　　　　　　　
平野佑佳, 本橋輝樹, 鱒渕友治, 吉川信一, 大島一典, 瀬戸山亨
日本セラミックス協会年会講演予稿集, 2012年
2012年 - 2012年

層状Li-Nb酸窒化物における超伝導　　　　　　　　　　　　　　　
本橋輝樹, 伊藤正彦, 分島亮, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集, 2012年
2012年 - 2012年

ゲル化窒化法によるGa_1-xAl_x(O,N)_yの合成における遷移金属添加効果　　　　　　　　　　　　　　　
山岡諒平, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2012年
2012年 - 2012年

LiNb₃O₈をアンモニア窒化した酸窒化物の合成,結晶構造と電磁気的性質　　　　　　　　　　　　　　　
伊藤正彦, 本橋輝樹, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2012年
2012年 - 2012年

鎖状構造を持つK₂TiO₃の酸性溶液への溶解機構と溶存状態　　　　　　　　　　　　　　　
鱒渕友治, 宮崎涼, 菊地拓希, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2012年
2012年 - 2012年

酸素貯蔵材料BaYMn₂O_5+δ(δ=0~1)の酸素吸収放出挙動　　　　　　　　　　　　　　　
上田拓, 本橋輝樹, 鱒渕友治, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2012年
2012年 - 2012年

酸窒化ガリウムナノファイバーの結晶成長と光・電気特性　　　　　　　　　　　　　　　
鱒渕友治, 山岡諒平, 本橋輝樹, 吉川信一, 李雄, 渡辺健太郎, 関口隆史, 桐原和大
日本セラミックス協会第24回秋季シンポジウム, 2011年09月07日, 日本語, 口頭発表（一般）
［国内会議］

Water soluble K2TiO3 for granular titanium oxide in silica matrix　　　　　　　　　　　　　　　
Yuji Masubuchi, Ryo Miyazaki, Hiroki Kikuchi, Teruki Motohashi, Shinichi Kikkawa
ADMP 2011, 2011年07月15日, 英語, 口頭発表（一般）
［国際会議］

Gallium Oxynitride Nanowire　　　　　　　　　　　　　　　
R. Yamaoka, Y. Masubuchi, T. Motohashi, K. Kirihara, W. Lee, T. Sekiguchi, S. Kikkawa
Engineering Ceramics 2011, 2011年05月08日, 英語, 口頭発表（一般）
［国際会議］

Local anionic ordering and anisotropic displacement in dielectric perovskite SrTaO2N
ZHANG Ya‐Ru, MOTOHASHI Teruki, MASUBUCHI Yuji, KIKKAWA Shinichi
日本セラミックス協会年会講演予稿集, 2011年03月16日, 英語

ペロブスカイト型酸窒化物SrTaO₂Nの結晶構造解析および誘電特性評価　　　　　　　　　　　　　　　
張雅茹, 本橋輝樹, 鱒渕友治, 吉川信一
日本金属学会講演概要(CD-ROM), 2011年
2011年 - 2011年

種結晶を用いた酸窒化ガリウム長尺ナノファイバーの結晶成長　　　　　　　　　　　　　　　
山岡諒平, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集, 2011年
2011年 - 2011年

酸窒化ガリウムナノファイバーの結晶成長とその形態制御　　　　　　　　　　　　　　　
山岡諒平, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集, 2011年
2011年 - 2011年

ブラウンミラーライト型Ca₂(Al_xMn_1-x)₂O_5+δ(x=0.5~0.67,δ=0~0.5)の合成と酸素吸収放出特性　　　　　　　　　　　　　　　
平野佑佳, 本橋輝樹, 鱒渕友治, 大島一典, 瀬戸山亨, 吉川信一
日本化学会北海道支部夏季研究発表会講演要旨集, 2011年
2011年 - 2011年

高周波スパッタCu₃NおよびFe-Si-O薄膜への微構造形成　　　　　　　　　　　　　　　
澤田亮典, 鱒渕友治, 本橋輝樹, 吉川信一, 佐々木正秀
日本化学会北海道支部夏季研究発表会講演要旨集, 2011年
2011年 - 2011年

酸素欠損ペロブスカイト型マンガン酸化物の顕著な酸素貯蔵能　　　　　　　　　　　　　　　
本橋輝樹, 上田拓, 平野佑佳, 鱒渕友治, 吉川信一, 大島一典, 瀬戸山亨
日本セラミックス協会秋季シンポジウム講演予稿集, 2011年
2011年 - 2011年

Ni-Nb系酸窒化物の結晶構造と超伝導特性　　　　　　　　　　　　　　　
伊藤正彦, 本橋輝樹, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集, 2011年
2011年 - 2011年

ダブルペロブスカイト型BaYMn₂O_5+δにおける酸素吸収放出の速度論研究　　　　　　　　　　　　　　　
上田拓, 本橋輝樹, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集, 2011年
2011年 - 2011年

窒化ニオブの結晶構造および超伝導性に及ぼす典型元素M(M=Mg,Al,Si)-酸素共ドープ効果　　　　　　　　　　　　　　　
大橋良央, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2011年
2011年 - 2011年

層状構造を持つ蛍光体ホストCaGdAlO₄における窒素部分置換体の合成　　　　　　　　　　　　　　　
畑智将, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2011年
2011年 - 2011年

低温窒化合成したα-Feを含むα”-Fe₁₆N₂微粉体の磁気特性　　　　　　　　　　　　　　　
山下祥平, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2011年
2011年 - 2011年

Crystal Growth of Gallium Nanofibers in Sub-mm Length　　　　　　　　　　　　　　　
Y. Masubchi, R. Yamaoka, T. Motohashi, S. Kikkawa
ICC-3, 2010年11月14日, 英語, ポスター発表
［国際会議］

Photoluminescence Property and Crystal Structure of Layered Aluminium Oxynitride Prepared through Citrate Route
HATA Tomoyuki, MASUBUCHI Yuji, MOTOHASHI Teruki, KIKKAWA Shinichi
日本セラミックス協会秋季シンポジウム講演予稿集, 2010年11月14日, 英語

Synthesis of AgTaN2 by exchange reaction
MIURA Akira, LOWE Michael, LEONARD Brian M, MASUBUCHI Yuji, KIKKAWA Shinichi, DRONSKOWSKI Richard, DISALVO Francis J
日本セラミックス協会秋季シンポジウム講演予稿集, 2010年11月14日, 英語

Oxynitrides as Emerging Functional Materials
KIKKAWA Shinichi, MASUBUCHI Yuji, MOTOHASHI Teruki, TAKEDA Takashi
日本セラミックス協会秋季シンポジウム講演予稿集, 2010年11月14日, 英語

Crystal Growth of Gallium Oxynitride Nanofibers in Sub-mm Length
MASUBUCHI Yuji, YAMAOKA Ryohei, MOTOHASHI Teruki, KIKKAWA Shinichi
日本セラミックス協会秋季シンポジウム講演予稿集, 2010年11月14日, 英語

Magnetite prepared in benzyl alcohol for the preparation of Fe16N2 with large magnetization　　　　　　　　　　　　　　　
Y. Masubuchi, S. Yamashita, T Motohashi, S. Kikkawa, M. Niederberger
ICCPS-11, 2010年08月29日, 英語, 口頭発表（一般）
［国際会議］

Crystallization and Magnetic Property of Iron Oxide Nano-particles Precipitated in Silica Glass Matrix　　　　　　　　　　　　　　　
Y. Masubuchi, Y. Sato, T Motohashi, S. Kikkawa
ICCPS-11, 2010年08月29日, 英語, 口頭発表（一般）
［国際会議］

シリカガラスマトリックスからの酸化鉄微粒子の結晶化　　　　　　　　　　　　　　　
鱒渕友治, 佐藤芳浩, 本橋輝樹, 吉川信一
日本セラミックス協会2010年年会, 2010年03月22日, 日本語, 口頭発表（一般）
［国内会議］

Preparation and dielectric properties of perovskite oxynitride SrTaO2N
ZHANG Yaru, MOTOHASHI Teruki, MASUBUCHI Yuji, KIKKAWA Shinichi
日本セラミックス協会年会講演予稿集, 2010年03月22日, 英語

Formation of gallium oxynitride nanofiber using the amorphous Ni-Ga oxide and NiGa2O4 precursors　　　　　　　　　　　　　　　
Y. Masubuchi, T. Motohashi, S. Kikkawa, F. Tessier
第48回セラミックス基礎科学討論会, 2010年01月12日, 英語, 口頭発表（一般）
［国内会議］

ダブルペロブスカイト型BaYMn₂O_5+δの酸素貯蔵能　　　　　　　　　　　　　　　
本橋輝樹, 上田拓, 鱒渕友治, 吉川信一, 滝口真, 瀬戸山亨, 大島一典
日本セラミックス協会年会講演予稿集, 2010年
2010年 - 2010年

酸窒化ガリウムナノファイバーの結晶成長　　　　　　　　　　　　　　　
山岡諒平, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会北海道支部夏季研究発表会講演要旨集, 2010年
2010年 - 2010年

ペロブスカイト型酸窒化物SrNbO₂NのLaによるAサイト置換効果　　　　　　　　　　　　　　　
小宮山卓史, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会北海道支部夏季研究発表会講演要旨集, 2010年
2010年 - 2010年

ダブルペロブスカイト型マンガン酸化物BaYMn₂O_5+δの酸素吸収放出特性　　　　　　　　　　　　　　　
上田拓, 本橋輝樹, 鱒渕友治, 吉川信一
日本化学会講演予稿集, 2010年
2010年 - 2010年

ゲル化窒化法を用いたペロブスカイト型Sr_1-xLa_xNb(O,N)₃の合成とその電気特性　　　　　　　　　　　　　　　
小宮山卓史, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会講演予稿集, 2010年
2010年 - 2010年

層状コバルト酸化物Li_xCoO₂(3):電気抵抗率測定　　　　　　　　　　　　　　　
杉本雄太, 本橋輝樹, 鱒渕友治, 笹川崇男, 山内尚雄, 山内尚雄, 吉川信一
応用物理学関係連合講演会講演予稿集(CD-ROM), 2010年
2010年 - 2010年

層状コバルト酸化物Li_xCoO₂(4):熱電変換特性と電子構造　　　　　　　　　　　　　　　
本橋輝樹, 杉本雄太, 鱒渕友治, 笹川崇男, 山内尚雄, 山内尚雄, 吉川信一
応用物理学関係連合講演会講演予稿集(CD-ROM), 2010年
2010年 - 2010年

α′′-Fe₁₆N₂合成原料としてのベンジルアルコール中で生成するマグネタイト微粒子　　　　　　　　　　　　　　　
山下祥平, 本橋輝樹, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集, 2010年
2010年 - 2010年

遷移金属窒化物の熱準安定性を用いた磁性体微構造薄膜の形成　　　　　　　　　　　　　　　
齋藤亮治, 鱒渕友治, 本橋輝樹, 吉川信一, 佐々木正秀
セラミックス基礎科学討論会講演要旨集, 2010年
2010年 - 2010年

酸窒化ペロブスカイトABO₂N(A=Sr,Eu,B=Ta,Nb)のゲル化窒化合成　　　　　　　　　　　　　　　
吉川信一, ZHANG Y., 浜出陽平, 小宮山卓史, 鱒渕友治, 本橋輝樹, 武田隆史
セラミックス基礎科学討論会講演要旨集, 2010年
2010年 - 2010年

MAGNETORESISTANCE ON POST-ANNEALED Fe70Co30-AlN SPUTTER DEPOSITED THIN FILM　　　　　　　　　　　　　　　
Yuji Masubuchi, Yuki Hirokawa, Teruki Motohashi, Shinichi Kikkawa
ICCE-17, 2009年07月26日, 英語, 口頭発表（一般）
［国際会議］

LUMINESCENCE OF Eu DOPED ALUMINUM AND ALUMINOSILICATE OXYNITRIDES PREPARED THROUGH CITRATE ROUTE.　　　　　　　　　　　　　　　
Yuji. Masubuchi, Mitsue Yoshikawa, Naoya Hatta, Takashi Takeda, Shinichi Kikkawa
ISNT 2009, 2009年03月15日, 英語, 口頭発表（一般）
［国際会議］

Photoluminescence and Structure of Eu2+ doped Apatite-type Lanthanum Silicon Oxynitride
MASUBUCHI Yuji, MOTOHASHI Teruki, KIKKAWA Shinichi
セラミックス基礎科学討論会講演要旨集, 2009年01月08日, 英語
［国内会議］

高周波スパッタ法による酸化鉄-シリカ複合膜の生成と磁気的性質　　　　　　　　　　　　　　　
佐藤芳浩, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会講演予稿集, 2009年
2009年 - 2009年

酸化鉄微粒子分散シリカ薄膜における粒径と結晶相の制御　　　　　　　　　　　　　　　
佐藤芳浩, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集, 2009年
2009年 - 2009年

層状コバルト酸化物Li_xCoO₂(2):熱起電力測定　　　　　　　　　　　　　　　
杉本雄太, 本橋輝樹, 鱒渕友治, 山内尚雄, 山内尚雄, 吉川信一
応用物理学関係連合講演会講演予稿集, 2009年
2009年 - 2009年

層状コバルト酸化物Li_xCoO₂(1):合成および磁気特性評価　　　　　　　　　　　　　　　
本橋輝樹, 杉本雄太, 鱒渕友治, 菅野了次, KARPPINEN M., KARPPINEN M., 山内尚雄, 山内尚雄, 山内尚雄, 吉川信一
応用物理学関係連合講演会講演予稿集, 2009年
2009年 - 2009年

ゲル化窒化合成した層状酸窒化アルミニウムの蛍光特性と窒素ドープ効果　　　　　　　　　　　　　　　
畑智将, 鱒渕友治, 本橋輝樹, 吉川信一
日本化学会北海道支部夏季研究発表会講演要旨集, 2009年
2009年 - 2009年

YBaCo₄O_7+δの酸素吸収及び,放出特性に対するAl置換効果　　　　　　　　　　　　　　　
小宮山卓史, 本橋輝樹, 鱒渕友治, 吉川信一
日本化学会北海道支部夏季研究発表会講演要旨集, 2009年
2009年 - 2009年

ペロブスカイト型タンタル酸窒化物Ca_1-xEu_xTa(O,N)₃の構造相転移　　　　　　　　　　　　　　　
本橋輝樹, 浜出陽平, 鱒渕友治, 吉川信一, 武田隆史, 村井啓一郎, 吉朝朗
日本セラミックス協会秋季シンポジウム講演予稿集, 2009年
2009年 - 2009年

ニオブ系酸窒化物超伝導体のゲル化窒化合成　　　　　　　　　　　　　　　
大橋良央, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集, 2009年
2009年 - 2009年

高周波スパッタ析出したFe₇₀Co₃₀-Al窒化物のポストアニール薄膜における構造と電磁気的性質　　　　　　　　　　　　　　　
広川祐樹, 鱒渕友治, 本橋輝樹, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2009年
2009年 - 2009年

低温窒化法で合成した巨大磁化Fe₁₆N₂の磁気特性　　　　　　　　　　　　　　　
山下祥平, 鱒渕友治, 吉川信一, 小山佳一
東北大学金属材料研究所強磁場超伝導材料研究センター年次報告, 2009年
2009年 - 2009年

窒化コバルト薄膜へのレーザー描画による微構造形成　　　　　　　　　　　　　　　
斎藤亮治, 鱒渕友治, 本橋輝樹, 吉川信一
日本セラミックス協会年会講演予稿集, 2009年
2009年 - 2009年

ゲル化窒化法による酸窒化ガリウムへのCoまたはNi添加効果　　　　　　　　　　　　　　　
宮明杏実, 鱒渕友治, 本橋輝樹, 吉川信一, 武田隆史
日本セラミックス協会年会講演予稿集, 2009年
2009年 - 2009年

Eu doped Aluminum and Aluminosilicate Oxynitride Phosphor Prepared through Citrate Route.　　　　　　　　　　　　　　　
Yuji Masubuchi, Mitsue Yoshikawa, Naoya Hatta, Takashi Takeda, Shinichi Kikkawa
IUMRS-ICA 2008, 2008年12月09日, 英語, 口頭発表（一般）
［国際会議］

Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum based Compound Prepared through Citrate Route.　　　　　　　　　　　　　　　
Yuji Masubuchi, Shinichi Yamamoto, Takashi Takeda, Shinichi Kikkawa
FGM2008, 2008年09月22日, 英語, 口頭発表（一般）
［国際会議］

Luminescence of Eu-doped b- and 15R- SiAlON Prepared through Citrate Route.　　　　　　　　　　　　　　　
Yuji Masubuchi, Mitsue Yoshikawa, Takashi Takeda, Shinichi Kikkawa
STAC2, 2008年05月30日, 英語, 口頭発表（一般）
［国際会議］

Eu添加した15R AlN-polytypoid蛍光体の合成と発光特性　　　　　　　　　　　　　　　
ZHU Xinwen, 鱒渕友治, 吉川信一
日本セラミックス協会秋季シンポジウム講演予稿集, 2008年
2008年 - 2008年

ペロブスカイト型酸窒化タンタルにおける酸素・窒素含有量　　　　　　　　　　　　　　　
浜出陽平, 鱒渕友治, 武田隆史, 吉川信一
日本化学会講演予稿集, 2008年
2008年 - 2008年

層状コバルト酸化物CoO₂及びLi_xCoO₂の電気化学合成とその電子構造　　　　　　　　　　　　　　　
本橋輝樹, 杉本雄太, 鱒渕友治, 吉川信一, 山内尚雄, KARPPINEN M., 菅野了次, ZHENG G.-Q., 川崎慎司
日本セラミックス協会秋季シンポジウム講演予稿集, 2008年
2008年 - 2008年

ゲル化窒化合成した複金属酸窒化物A_1-xB_xO_yN_z(A:Nb,B:Al,Mg)の結晶構造および物性におけるアニール効果　　　　　　　　　　　　　　　
大橋良央, 山本伸一, 鱒渕友治, 本橋輝樹, 吉川信一
粉体粉末冶金協会講演概要集, 2008年
2008年 - 2008年

Co,Ni又はZnイオンを共存させて生成した酸窒化ガリウム　　　　　　　　　　　　　　　
宮明杏実, 鱒渕友治, 本橋輝樹, 吉川信一, 武田隆史
日本セラミックス協会秋季シンポジウム講演予稿集, 2008年
2008年 - 2008年

酸窒化ニオブおよびタンタル系化合物のゲル化窒化合成と構造および物性　　　　　　　　　　　　　　　
山本伸一, 鱒渕友治, 武田隆史, 吉川信一
セラミックス基礎科学討論会講演要旨集, 2008年
2008年 - 2008年

SiO₂マトリックスを用いたε-Fe₂O₃の合成　　　　　　　　　　　　　　　
佐藤芳浩, 鱒渕友治, 吉川信一
日本化学会北海道支部研究発表会講演要旨集, 2008年
2008年 - 2008年

Fe₇₀Co₃₀合金-Al複合ターゲットの反応性スパッタによる窒化物薄膜の形成とポストアニール　　　　　　　　　　　　　　　
広川祐樹, 鱒渕友治, 吉川信一
日本セラミックス協会年会講演予稿集, 2008年
2008年 - 2008年

ゲル化窒化法によるSiAlONの合成と蛍光体への応用　　　　　　　　　　　　　　　
葭川充江, 鱒渕友治, 武田隆史, 吉川信一
日本セラミックス協会年会講演予稿集, 2008年
2008年 - 2008年

M型及びW型バリウムフェライト-ヘマタイト磁性複合体の合成と性質　　　　　　　　　　　　　　　
斎藤亮治, 鱒渕友治, 吉川信一
日本化学会北海道支部研究発表会講演要旨集, 2008年
2008年 - 2008年

酸窒化ガリウムの生成に及ぼすCo,Ni,Znの添加効果　　　　　　　　　　　　　　　
宮明杏実, 鱒渕友治, 吉川信一
日本化学会講演予稿集, 2008年
2008年 - 2008年

アニオン付加・脱離反応を伴う複合酸化物の複合アニオン化と新規光・電材料の創製
科学研究費助成事業
2024年04月01日 - 2028年03月31日
佐藤 泰史, 鱒渕 友治, 賈 軍軍
日本学術振興会, 基盤研究(B), 岡山理科大学, 24K01169

多原子アニオン化合物を用いた環境応答発光材料の開発　　　　　　　　　　　　　　　
研究助成
2022年04月 - 2024年03月
公益財団法人旭硝子財団, 研究代表者

高結晶性酸窒化物蛍光体の省エネルギー合成プロセスの開発　　　　　　　　　　　　　　　
研究助成
2022年04月 - 2023年03月
公益財団法人池谷科学技術財団, 研究代表者

高結晶性な酸窒化物微粒子のフラックス合成　　　　　　　　　　　　　　　
研究助成
2022年04月 - 2023年03月
公益財団法人ホソカワ粉体工学振興財団, 研究代表者

新規複合アニオン化合物の創製：物質合成と設計指針の確立
科学研究費助成事業 新学術領域研究(研究領域提案型)
2016年06月30日 - 2021年03月31日
荻野 拓, 陰山 洋, 垣花 眞人, 稲熊 宜之, 殷 しゅう, 鱒渕 友治, 本郷 研太, 小林 亮
本研究では、複合アニオン化合物という新たな物質系に対し、系統的な新物質探索および新合成手法の開発を行うことで、この無機化学の新たな学術領域の基礎学理を構築し、創エネ・省エネに貢献する革新的な新材料の創成を目的としている。本年度は、酸水素化物の特異性の追求、窒化物新合成法の活用、様々な物質系での系統的な物質探索を行い、これら新物質の光触媒や蛍光体、誘電体といった機能開拓を目指した。また合成・解析の様々な局面での計算科学の活用を試みた。外殻軌道がs軌道からなる唯一のアニオンであるヒドリドの特異性に着目した研究では、酸水素化物LnHOが、圧力下でヒドリドの配位数が減少するという、従来の常識では考えられない変化を示すことが明らかになった。また本研究では固体窒素源を用いる酸窒化物の新規合成法を開発したが、この手法が様々な物質系に適用できること、簡便なだけでなく粒径の制御など実用面でも優れた特徴を有することがわかった。新物質開発では、6H型酸水素化物ペロブスカイト、ハロゲンやニクトゲンなどの非常に大きなアニオンを含む複合アニオン化合物、Pbなど非対称カチオンを含む複合アニオン化合物の探索、トポケミカル法による層状化合物の開発などを行った。またこれまで複合アニオンのアニオンとしては主に単体イオンのみだったが、今年度は(CN2)2+、(OH)-といったポリアニオンを含む複合アニオンの開発も活発に行い、これらポリアニオンの特異性に着目した機能探索も行った。計算科学の活用もこれまで以上に押し進め、特に本研究の主題の一つであったアニオン配列の解明にDFT計算が非常に有効であることを見出した。公募研究各グループとの連携も積極的に行った。これらの成果により、2019年度は研究計画A01単体で60件以上の招待・基調講演を行い、100報近い論文を出版した。
日本学術振興会, 新学術領域研究(研究領域提案型), 国立研究開発法人産業技術総合研究所, 16H06439

窒化炭素を用いた機能性酸窒化物の新規合成手法の開発　　　　　　　　　　　　　　　
研究助成
2017年04月 - 2018年03月
公益財団法人日本板硝子材料工学助成会, 研究代表者

酸素窒素の配列で物性を制御する新しい機能性無機材料の開発
科学研究費助成事業 若手研究(B)
2015年04月01日 - 2017年03月31日
鱒渕 友治, 吉川 信一
本研究では、ペロブスカイト型酸窒化物における酸素と窒素の比率や分布を制御する手法を開発し、それらが誘電性に与える影響を調べることを目的とした。①ペロブスカイト型酸窒化物固溶体La1-xSrxTiO2+xN1-xを合成し、窒素のシス型配列がx=0.2でも維持されることを明らかにした。さらにTi周りの多面体の歪みは増加し、この局所構造が誘電率の向上に寄与すると考えられた。②窒化炭素C3N4を用いたペロブスカイト型酸窒化物の新しい合成手法を開発した。この手法ではアンモニア窒化法よりも低温の800℃でSrTaO2Nが得られ、生成物の格子定数変化から酸素窒素配列が異なる結晶構造が得られた可能性がある。
日本学術振興会, 若手研究(B), 北海道大学, 研究代表者, 競争的資金, 15K17915

水の熱化学分解による水素ガス生成のための低温活性型・酸素貯蔵材料の開発
科学研究費助成事業
2014年04月01日 - 2017年03月31日
本橋 輝樹, 齋藤 美和, 吉川 信一, 鱒渕 友治, 陰山 洋, 久保田 佳基
本研究では、水を熱化学分解して水素ガスを発生させる機能性セラミックス：「酸素貯蔵材料」の設計・開発を行った。ダブルペロブスカイト型BaLnMn2O5（Ln: 希土類元素）において、500℃で水分解による水素生成活性を確認した。水素生成反応活性はLn種に強く依存し、Ln3+イオン半径が大きいほどBaLnMn2O5の反応活性は高かった。量子化学計算に基づく熱力学的エネルギー解析により、本材料の酸化還元活性がLnサイトの等価数元素置換により強く影響を受けることが判明し、化学組成制御が材料テーラリングにおいて有望であると結論付けた。
日本学術振興会, 基盤研究(B), 26288104

新しいペロブスカイト型酸窒化物のＡサイト置換効果による誘電性および焼結性に関する研究　　　　　　　　　　　　　　　
研究助成
2016年04月 - 2017年03月
公益財団法人大倉和親記念財団, 研究代表者

巨大誘電率をもつ酸窒化物ペロブスカイトにおける機能化プロセシング
科学研究費助成事業 基盤研究(A)
2012年04月01日 - 2015年03月31日
吉川 信一, 本橋 輝樹, 鱒渕 友治
酸窒化物ペロブスカイトSrTaO2NおよびLaTiO3では、Bサイトイオン周りのO4N2八面体中でN3-イオンがシス型に配位し誘電性を発現する源となる可能性のある局所的分極を生じることを、中性子回折法によって明らかにした。それぞれ950℃および800℃付近から、ペロブスカイト型構造を保ったまま、約30％の窒素を放出した。SrCN2など高温でSrとNの双方を補充できる焼結助剤が、誘電体セラミックスを作製する上で有効なことを見出した。
日本学術振興会, 基盤研究(A), 北海道大学, 連携研究者, 競争的資金, 24245039

ペロブスカイト型酸窒化物固溶体の誘電特性および焼結体の作製　　　　　　　　　　　　　　　
研究助成
2013年06月 - 2014年05月
公益財団法人村田学術振興財団, 研究代表者

層状構造をもつ遷移金属オキシナイトライドの合成と新奇超伝導体の探索
科学研究費助成事業
2012年04月01日 - 2014年03月31日
本橋 輝樹, 吉川 信一, 鱒渕 友治
本研究では、オキシナイトライドにおいて層状構造を持つ新奇超伝導体を創製することを目的とし、LiとNbが秩序配列したオキシナイトライドに着目した。
LiNb3O8をアンモニア窒化して六方晶Li0.88Nb3.0(O0.13N0.87)4を合成した。本物質は八面体サイトと三角プリズムサイトが交互に積層する構造を持ち、八面体サイトにはLiとNbが約4 : 6の比で共存し、三角プリズムサイトはほぼNbのみが占有することが判明した。
本物質は金属的伝導性を示し、約3 Kから電気抵抗率が急激に低下した。さらに、この温度以下で大きな反磁化と比熱の異常が観測され、本物質が新規超伝導体であることが強く示唆された。
日本学術振興会, 挑戦的萌芽研究, 北海道大学, 24654094

酸窒化物ナノワイヤの高品質化と多機能化
科学研究費助成事業 若手研究(B)
2012年04月01日 - 2014年03月31日
鱒渕 友治, 吉川 信一, 本橋 輝樹
本研究では、紫外域に特異な発光を示す酸窒化ガリウムナノワイヤの高品質化とそれを用いた物性評価を目的とした。①Znを固溶させた酸窒化ガリウムナノワイヤをゲル化窒化法で合成し、陽イオン欠損量の減少による結晶性の向上を確認した。又、②ZnOと酸窒化ガリウムナノワイヤを真空封管中加熱する手法で3%程度Znが均一に固溶したGa-Zn酸窒化物ナノワイヤを合成し、③カソードルミネッセンス測定において3.4eVと2.7eVに同時に発光を確認した。Znの固溶により結晶性は向上し、複数のカソードルミネッセンス発光は酸窒化ガリウム中のZnとOによる準位と関連していると思われる。
日本学術振興会, 若手研究(B), 北海道大学, 研究代表者, 競争的資金, 24750196

窒化物系ナノワイヤの育成と評価
科学研究費助成事業 挑戦的萌芽研究
2011年 - 2012年
吉川 信一, 本橋 輝樹, 鱒渕 友治
微量のニッケルやコバルトを共存させて酸窒化ガリウムを合成すると、これらの遷移金属窒化物の熱的な準安定性が関与して、酸窒化ガリウムナノワイヤが生成する。これを電子顕微鏡観察してウルツ鉱型のc面にそってナノワイヤは伸びており、その積層様式は閃亜鉛鉱型との乱層構造となっていることが明らかになった。また窒化ガリウムよりも高エネルギーな4.3eVに弱いバンド端吸収と、2.7eVには酸素が関与する青色発光を観察した。
日本学術振興会, 挑戦的萌芽研究, 北海道大学, 連携研究者, 競争的資金, 23655188

遷移金属をベースにした新規酸素貯蔵材料の開発とその応用展開
科学研究費助成事業
2010年 - 2011年
本橋 輝樹, 吉川 信一, 鱒渕 友治, 瀬戸山 亨, 大島 一典
多量の酸素を低温で可逆に吸収放出する金属酸化物は「酸素貯蔵材料」と呼ばれ、酸化還元反応の精密制御を可能にする機能性材料としてエネルギー・環境分野での応用が期待されている。本研究では、遷移金属酸化物において顕著な酸素吸収放出特性を示す材料の開発研究を行った。マンガンをベースにした新規酸素貯蔵材料:BaYMn_2O_<5+δ>およびCa_2(AlxMn_<1-x>)_2O_<5+δ>を開発し、酸素吸収放出メカニズムを検討した。
日本学術振興会, 若手研究(B), 北海道大学, 22750181

ゲル化窒化法による複金属酸窒化物系高温超伝導体の創出
科学研究費助成事業 基盤研究(A)
2009年 - 2011年
吉川 信一, 本橋 輝樹, 鱒渕 友治
岩塩型の窒化ニオブが、超伝導体(Tc=17K)であることに着目した。ニオブと異種金属陽イオンが均一に混合したアモルファス酸化物の混合物および複金属酸化物をアンモニア雰囲気中で焼成し、以下の新しい酸窒化物および窒化物超伝導体を発見した。(1)岩塩型(Nb_<0.95>Mg_<0.05>)(N_<0.92>O_<0.08>),(Nb_<0.89>Al_<0.11>)(N_<0.84>O_<0.16>),(Nb_<0.87>Si_<0.09>□_<0.04>)(N_<0.87>O_<0.13>)、(2)LiTa_3N_4型(Li_<0.88>□_<0.12>)Nb_3(N_<0.87>O_<0.13>)_4、(3)岩塩型(Nb_<0.5>Ti_<0.5>)N板状晶
日本学術振興会, 基盤研究(A), 北海道大学, 連携研究者, 競争的資金, 21245047

金属窒化物のレーザー熱分解法によるメタマテリアル生成
科学研究費助成事業 挑戦的萌芽研究
2008年 - 2009年
吉川 信一, 鱒渕 友治
3d遷移金属窒化物は熱準安定性であり、数百℃以上に加熱すると窒素を放出して遷移金属が析出する。析出を制御してできる遷移金属の微細な構造によって発現する性質を利用するメタマテリアルを目指して研究を進め、以下のような研究成果を上げることができた。
1)高周波スパッタ法で石英ガラス基板上に成膜したウルツ鉱型Al_<0.5>Fe_<0.5>N薄膜を450～600℃でポストアニールして、α-Fe微粒子がAlN中に分散したグラニュラー薄膜を得た。これらのグラニュラー薄膜はマイクロ波領域で強磁性共鳴を示すところから、負の透磁率が実規した。なおα-Fe微粒子粒子径の関係で、450℃でアニールした場合に最も大きな共鳴吸収が観測された。
2)熱拡散性のよいAlNを下地膜とした石英ガラス基板上に成膜した閃亜鉛鉱型Fe_<0.7>Al_<0.3>N薄膜(約2kΩ)に、窒素雰囲気中で波長809nmの半導体レーザーを出力2.5W、走査速度1mm/sでレーザー描画して、線幅200μmで導電性の良いα-Feの微細線(約300Ω)を引くことができた。金属中ではプラズマ周波数以下では誘電率が負になる。
これらの負の透磁率を負の誘電率と組み合わせることによって、負の屈折率が実現できると考えられる。
日本学術振興会, 挑戦的萌芽研究, 北海道大学, 連携研究者, 競争的資金, 20655045

アルミニウム系酸窒化物における希土類発光中心の構造制御
科学研究費補助金
2008年 - 2008年
吉川 信一, 鱒渕 友治
LEDやディスプレーなどの様々な用途に向けて耐久性のある高輝度蛍光体が求められている。ユーロピウムを共存させて酸窒化アルミニウムをゲル化窒化合成すると、マグネトプラムバイト型の結晶構造を持つと思われる化合物が微量生成した。とりわけ0.5 at%ユーロピウムを添加した生成物が複数波長で強い青色の発光を示した研究実績を踏まえ、本研究ではAlN擬似多形15R相siAl_4O_2N_4にEu^<2+>をドープした蛍光体を合成して蛍光特性を調べた。1) Si_3N_4/AIN/Al(NO_3)_3=1/8/4の原料組成比を1/12.8/6.4とし0.5at%ユーロピウムを添加したゲル化窒化生成物を1750℃で3時間ホットプレス処理すると、15Rポリタイポイドが主相でα-A1_2O_3を含む混合物が得られ、450nm付近で青色発光した。また2)α-Si_3N_4, α-A1_2O_3, AINおよびEu_2O_3を原料とし1800〜1850℃でホットプレスする固相反応法によって、15R相siAI_4O_2N_4にユーロピウムドープした蛍光体の単一相が生成した。440nm付近に最大強度をもち450nm付近に肩のあるEu^<2+>の4f^65d→4f^7に帰属される発光ピークをもつ青色発光を示した。これらの実験結果より、ポリタイポイド15R相SiAl_4O_2N_2 : Eu^<2+>は、紫...
文部科学省, 北海道大学, 連携研究者, 競争的資金, 20900101

遷移金属二酸化物の電気化学的強酸化合成とその電子構造の解明
科学研究費助成事業
2007年 - 2008年
本橋 輝樹, 山内 尚雄, カルピネン マーリット, 菅野 了次, 鄭 国慶, 川崎 慎司, 吉川 信一, 鱒渕 友治
本研究では、電子相関効果やスピンフラストレーション効果が期待される層状遷移金属二酸化物の電気化学的強酸化合成とその電子構造の解明を目的とした。特に、巨大熱起電力や超伝導の発見により注目を集めている層状コバルト酸化物の一種であるLixCoO2系について、Li量 (x) を幅広く制御した高品質試料の合成と物性評価を行い、Li量 (x) をパラメータとする電子状態図を構築した。
日本学術振興会, 若手研究(B), 19740201

ゲル化窒化法による金属酸窒化物の形成と機能発現
科学研究費助成事業 基盤研究(B)
2007年 - 2008年
吉川 信一, 本橋 輝樹, 鱒渕 友治
ゲル化窒化合成法により、様々な酸窒化物を創出した。酸化物および窒化物イオンが金属イオンと結合すると、それらの様々な相互配置によって、高い機能性の現れることを明らかにした。
1)酸窒化ガリウムでは3d遷移金属の種類によって特異なドープ挙動を示した。NiやCoはごく少量しかドープできないが、繊維状の結晶が生成した。
2)立方晶ペロブスカイトEuTaO_2Nは正方晶マイクロドメインの集合体であることが判明し、大きな誘電率の起源と考えられた。
3)Nb-Al系では、岩塩型の新しい複金属酸窒化物が生成した。1700℃でホットプレスによりポストアニールすると、超伝導体の体積分率は48%まで増加した。
日本学術振興会, 基盤研究(B), 北海道大学, 連携研究者, 競争的資金, 19350098