Sym1iesis of hydroxyapatite by sol-gel combustion method using tricarboxylic acid and diamide as a mixed fuel

摘要

Calcium hydroxyapatite was synthesized by sol-gel combustion method by employing urea and citric acid as a mixed fuel. Nitric acid was used as an oxidizer; calcium nitrate and di-ammonium hydrogen phosphate were taken as the calcium and phosphate precursor respectively. The influence of metal ion to fuel ratio on the phase evolution and morphology was studied. The synthesized powders were characterized by powder X-ray diffractometer for phase evolution and Fourier transform infrared spectrometer was used to find out the carbonate substitution in hydroxyl and phosphate sites. Thermal analysis was carried out to verify the phase transitions and thermal stability of the products. The result shows the influence of ratio of fuels on the auto ignition temperature as the auto ignition temperature of urea decreases by the addition of citric acid. In addition, the phase formation is found to vary with the metal ion to fuel ratio, irrespective of the initial metal ion to phosphate ratio.