Recent studies for the early stages of crystal formation from aqueous solution have shown that crystals grow not only by the monomer-by-monomer addition mechanisms described in the classical nucleation theory, but also by the aggregation of particles, ranging from multi-ion complexes to fully formed nanocrytals. These particle-based growth processes have been considered as "non-classical" crystallization pathways and attracted research especially in the field of biomineralization for the last 20 years, however physical and chemical understanding for these processes is still lacking. Here we review literature reports on this mechanism to provide a general view for this new concept.
Mgを含む合成モノハイドロカルサイト(MHC)試料と標準物質のXANES測定、Mgを含むMHCの第一原理計算、MHC中および溶液中のCa/Mg分配挙動の熱力学的解析から、MHC中のMgは非晶質Mg炭酸塩と、構造内を6配位で置換するMgのミクスチャーであることを示した。さらに分子レベルで明らかになったMgの存在状態に基づき、MHC中に含まれるMg含有量から、生成時の水質を定量的に制約する手法を提案した。