PREPARATION OF SIZE CONTROLLED, STOICHIOMETRIC AND BIORESORBABLE HYDROXYAPATITE NANOROD BY VARYING INITIAL pH, Ca/P RATIO AND SINTERING TEMPERATURE

To control the particle size, morphology and stoichiometry of hydroxyapatite (HAp) is very important in properties and applications. HAp plays a keyrole in the field of orthopedic and dental because of it’s appreciable host responses in the biological environment. The aqueous based sol-gel method has been employed to synthesis a size controlled HAp with nanorod like morphology. It has been found that the variation in molar concentration of initial sols and pH can be used to control the Ca/P ratio of the final product, crystallite size and surface morphology of the HAp. The stoichiometric (Ca/P=1.67) HAp nanorod (48-52 nm x 15-18 nm) has been achieved against initial molar concentration ratio of 1.72 and pH=11. Further, the optimised stoichiometric HAp nanorod is sintered at three different temperatures to investigate the effect of sintering temperature on morphology, microhardness and bioresorbability. The nanorod like morphology in the powder changed to a more equiaxed shape (spherical like morphology with size of 85.24 nm) after sintering. The crystallite size of HAp nanorod is increases with increase the pH and Ca/P ratio. Further, it has been observed that the hardness of the HAp nanorod increases with increase in the sintering temperature. (Received Deccamber 3, 2010; accepted January 15, 2011)