Investigations on the synthesis and crystallization of hydroxyapatite at low temperature

An easy method to crystallise homogenous HAP at physiological pH as well as powders of HAP and CPP at low temperature are described. Platy and spherulitic crystals of HAP were crystallised at the physiological pH using single diffusion method. Well‐defined platy crystals of hydroxyapatite were obtained at the physiological temperature and pH. These crystals were found to be pure and homogenous form of HAP without any contamination from the crystallising medium. Spherulitic crystals of HAP of approximately 3 mm in diameter were obtained in the presence of Fe at 47°C. A sol‐gel technique involving agarose is described for the preparation of hydroxyapatite and calcium pyrophosphate. Pure form of HAP was synthesised at 85°C and its sintering properties were also studied. At a temperature of 1200°C, the material gets completely converted to α‐calcium pyrophosphate. The samples were analysed by XRD, IR, TGA and SEM. The particle size of the synthesised powders was measured using the dynamic light scattering experiments.