Synthesis of hydroxyapatite whiskers by hydrolysis of α-tricalcium phosphate using microwave heating

Calcium hydroxyapatite (Ca10(PO4)6(OH)2, HAp) whiskers have been processed using microwave and conventional heating. During microwave heating, well developed whisker shaped HAp was formed by a hydrolysis reaction of α-Ca3(PO4)2 (α-TCP) at 70-90 °C for 6-15 h. The hydrolysis time required for complete conversion of α-TCP to HAp was half than that required for conventional heating. The morphology of the reaction product was controlled by varying the hydrolysis temperature and time. The reaction product obtained at 70 °C for 15 h exhibited a conversion rate ∼95% to HAp, and a whisker-like morphology with an aspect ratio >10 (≤0.2 μm in diameter), a specific surface area (SBET) of 5.34 m2 g−1 and a Ca/P molar ratio of 1.66.