Synthesis of calcium phosphate bioceramics by citrate gel pyrolysis method

Hydroxyapatite granules have been prepared by the pyrolysis of an amorphous polymeric precursor compound containing calcium–phosphate–nitrate–citrate species. The precursor phase on heating at around 550–650 °C turned into crystalline phase. The thermogravimetrical analysis (TGA/DTA) study revealed that the decomposition and crystallization is completed below 650 °C. Fourier transform infrared spectroscopy (FTIR) studies conducted on the precursor phase heated at various temperatures showed that the carbonate substitution occurred in the phosphate moieties at lower temperatures of heating. The X-ray diffractometry (XRD) revealed that the hydroxyapatite formation is highly uniform with respect to apatite phase. The scanning electron microscopy (SEM) showed that the product is highly porous.