Synthesis and characterization of biocompatible-nanohydroxyapatite crystals obtained by a modified sol-gel processing

A modified sol-gel process for synthesizing nanocrystalline hydroxyapatite powders (nHA) for biomedical applications, using tetrahydrated calcium nitrate [Ca(NO(3))(2)∙4H(2)O] and phosphorous pentoxide [P(2)O(5)] as precursor, is presented and discussed. The powders were washed and heat-treated at different temperatures and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The total process time reached with this modified process was less than 16 h. The results showed that there was an increment in size of the HA nanocrystals (nHA) when treated at different temperatures, ranging from 30 nm for the sample treated at 600°C to 500 nm for the sample heat-treated at 1,200°C.