Synthesis of Calcium Phosphate and Calcium Silicate Composites

Abstract

A one-step method for preparing composites based on calcium phosphates (CPs) and calcium silicates (CSs) with variable contents of the components is proposed. The combination of chemical analysis, X-ray powder diffraction, and simultaneous thermal analysis with mass-spectrometric detection (STA-MS) showed that the coprecipitation of salts from aqueous solutions yielded mixtures of poorly crystallized carbonate hydroxyapatite (CHA) and xonotlite with minor calcite. Scanning electron microscopy and low-temperature nitrogen adsorption showed that nanosized crystallites of these phases during crystallization were combined into mesoporous aggregates (the mean pore size was 6–11 nm) to form micrometer-sized bulk structures with a developed surface. Two-hour calcination of synthesis products at 1000°С yielded mixtures of well-crystallized Са₁₀(РО₄)₆(ОН)₂ and β-CaSiO₃.