Nano-sized hydroxyapatite powders prepared by flame spray pyrolysis

Nano-sized hydroxyapatite (HAp) powders with high crystallinity and appropriate stoichiometry were prepared by high-temperature flame spray pyrolysis process from the spray solutions with polyethylene glycol (PEG). The mean sizes of the HAp powders obtained from the spray solutions with PEG were changed from several tens to several hundreds nanometers according to the concentrations of PEG added to the spray solutions at a post-treatment temperature of 800 °C. In the TEM-EDX spectrum, the composition ratio of calcium and phosphorous components was 1.69. The HAp powders post-treated at a low temperature of 400 °C had fiber-like morphology. On the other hand, the post-treated HAp powders at temperatures of 600 and 1000 °C had each rod-like morphology with low aspect ratio and spherical-like morphology. The mean sizes of the HAp powders post-treated at temperatures of 600 and 1000 °C were each 32 and 213 nm.