Crystal growth and phase transformation in the precipitation of calcium phosphates

摘要: A survey of calcium phosphate precipitation in the neutral and slightly acidic pH range is presented. The concentration regions, within which precipitates are formed by direct crystallization via precursor phases defined. As examples, kinetics growth monohydrogen dihydrate (CaHPO4·2H2O, DCPD) amorphous (ACP) were followed at 25 °C. DCPD was precipitated from 0.15 M NaCl solutions constant 5. Precipitates heterogeneous nucleation. crystal process best described rate equation: dX/dt= 3.6 × 109X2/3([CaHPO4o]t–[CaHPO4o]s)3 where X amount per dm3 solution [CaHPO4o]t [CaHPO40]s concentrations soluble complex time t equilibrium. ACP prepared zero 7.2 ± 0.05 subsequent changes pH, particle diameter as a function time. homogeneous nucleation consisted spherical, approximately monodispersed particles. Agglomeration occurred early stages precipitation. Later, during period metastability ACP, number individual spherules approached value but their volume increased with first order supersaturation.