Morphological evolution of precipitates during transformation of amorphous calcium phosphate into octacalcium phosphate in relation to role of intermediate phase

Yuki Sugiura, Kazuo Onuma, Yuki Kimura, Hitoshi Miura, Katsuo Tsukamoto

研究成果: Contribution to journalArticle査読

15 被引用数 (Scopus)

抄録

Nucleation of amorphous calcium phosphate (ACP) and its phase transformation with a decrease in solution pH were investigated at a constant temperature of 32 °C. A solution containing a mixture of CaCl2 and KH2PO4 was prepared (initial pH=7.7), and a drop was sampled at a constant interval to observe the morphological evolution of the precipitates that formed in the solution. A gel-like solution structure formed immediately after mixing and contained a small amount of sea-urchin-like ACP spherulites (320 μm in size). These spherulites consisted of 1.510-μm-long flexible needles that formed simultaneously with numerous ACP spherical particles. They first transformed into β-tri calcium phosphate-like material (called pseudo β-TCP) and then into single crystals of octacalcium phosphate (OCP) without dissolution. The flexible needles in the spherulites changed into blade springs, then into flexible plates, and finally into rigid plates during the transformation. The OCP structure appeared in the pseudo β-TCP plates and gradually substituted for the β-TCP structure over time. The macroscopic spherulite morphology of the initial ACP remained unchanged during the phase transformation, suggesting that OCP is a pseudomorph of ACP. This feature was observed only when the ACP spherulites formed in the initial solution. Fiber-like aggregates consisting of β-TCP single crystals nucleated around the ACP spherical particles and grew over time. They survived until the final stage of the reaction, and OCP polycrystals formed in the mixture of β-TCP and ACP spheres. The OCP polycrystals gradually substituted for the ACP spheres without phase transformation of β-TCP into OCP.

本文言語英語
ページ(範囲)58-67
ページ数10
ジャーナルJournal of Crystal Growth
332
1
DOI
出版ステータス出版済み - 10 1 2011

All Science Journal Classification (ASJC) codes

  • 凝縮系物理学
  • 無機化学
  • 材料化学

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