CHARACTERIZATION AND THERMAL ANALYSIS OF HYDROXYAPATITE POWDER SYNTHESIZED BY SOL-GEL AND HYDROTHERMAL TECHNIQUE

Abstract

Hydroxyapatite (HA) is an inorganic bioceramic compound which is widely used in various biomedical applications, mainly in orthopaedics and dentistry due to its close similarities with inorganic mineral component of bone and teeth. The Sol-Gel technique to prepare HA has some desirable properties like molecular-level homogeneity, lower processing temperature and suitability to generate nanosized particles etc. Similarly, Hydrothermal technique has some added advantages over other techniques like it takes far fewer time and energy consuming steps than other techniques and is environmentally benign in nature. So, in the present work, Sol-Gel and Hydrothermal techniques have been used to synthesize ultrafine crystalline hydroxyapatite (HA) powders using two different chemical reagents, calcium nitrate tetrahydrate (Ca(NO3)2.4H20) and di-ammonium hydrogen phosphate ((NH4)2HPO4) as calcium and phosphorous precursors respectively. The effect of sintering on the development of HA was studied. The final powder was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Field emission scanning electron microscopy (FESEM) equipped with Energy dispersive spectroscopy (EDS) techniques to reveal its phase content, various types of bonds present in it, its morphology and composition respectively. The FESEM examination showed that the synthesized hydroxyapatite powders were composed of aggregates of angular nanosized hydroxyapatite particles. EDS analysis showed that the Ca/P ratio in HA powder was very close to the stoichiometric Ca/P ratio of 1.67. Transmittance bands corresponding to phosphate and hydroxyl functional groups, which are characteristic of hydroxyapatite, were confirmed by FTIR spectroscopy. Thermal (TG—DTA) analysis confirmed the thermal stability of the HA powder.