Processing of Hydroxyapatite by Biomimetic Process

Abstract

The present work deals with a novel chemical precipitation technique for synthesizing Hydroxyapatite (HAp- Ca10 (PO4)6 (OH) 2) by a Biomimetic method using calcium nitrate tetra hydrate Ca(NO3)2•4H2O and diammonium hydrogen phosphate salts (NH4)2HPO4 as precursors dissolved in synthetic body fluid (SBF) solutions at 37°C and pH of 7.4. The crystalline phase, chemical composition and crystallite size of the obtained samples, calcined at various temperatures 560°C, 750°C, 850°C, 1000°C, 1100°C and 1200°C for 2 hours, were characterized by X-ray powder diffraction (XRD). A considerable change in crystallite sizes is observed with change in calcination temperature. TG/DSC of raw powder shows that the as prepared powder has phase change in HAp at 4500C and the total weight loss on heating was 9.45%. The specific surface area of the prepared HAp powder was measured by BET. Thus in the present work the synthesized HAp is stable till 750°C. Above this temperature, HAp first decomposes to β-TCP, followed by its conversion to α-TCP above 1200°C.