Synthesis and Characterization of Hydroxyapatite–Wollastonite Composite Powders by Sol–Gel Processing

Composites of hydroxyapatite–wollastonite were synthesized by a sol–gel route using calcium acetate and triethyl phosphate as precursors of hydroxyapatite and high‐purity natural wollastonite added in ratios of 20, 50, and 80 wt%. These composites were characterized by thermal analysis, X‐ray diffraction, FT‐IR and Raman spectroscopy, and scanning and transmission electron microscopic techniques. Formation of hydroxyapatite occurs at a relatively low temperature, about 420°C, accompanied by calcium carbonate; wollastonite remains unreacted. The composites were purified by heat treatment to a higher temperature and washed with hydrochloric acid and distilled water, to produce B‐type carbonated hydroxyapatite–wollastonite composites as final products.