Synthesis and mechanical performance of biological-like hydroxyapatites

Synthesis of hydroxyapatites (HAP) with cosubstituted essential trace elements (Na, Mg, K, Cl, and F) of natural bone was performed through aqueous precipitation. The powders were characterized using elemental analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The results obtained proved that substituted elements play a crucial role in enhancing the thermal stability of the HAP phase until 1400 degrees C, when compared to the stoichiometric HAP which decomposed to alpha-tricalcium phosphate beyond 1200 degrees C. A noticeable amount of beta-TCP along with the HAP phase has also been detected after calcination at higher temperatures, which tended to increase with increasing the incorporation levels of trace elements. Significant improvements in the mechanical properties were obtained for sintered specimens of the cosubstituted hydroxyapatites in comparison to pure HAP.