Preparation of high-temperature stabilized β-tricalcium phosphate by heating deficient hydroxyapatite with Na4P2O7 · 10H2O addition

n this paper, the high-temperature stabilized β-tricalcium phosphate (βTCP, β-Ca3(PO4)2) were prepared by heating the deficient HAP (d-HAP, Ca10-x(HPO4)x(PO4)6-x(OH)2-x) with tetra-sodium diphosphate decahydrate (NP, Na4P2O7 · 10H2O) addition. The βTCP, d-HAP and d-HAP doped with 2.5, 5, 7.5 and 10 wt % NP were heated to different temperatures and were investigated by X-ray diffraction analysis (XRD) and Fourier-transformed infrared spectroscopy (FTIR). The results demonstrated that the HPO2-4 of d-HAP condensed into P2O4-7 occurred before 650°C. The P2O4-7 ions could be traced in the FTIR spectrum when the d-HAP was heated up to 750°C. The reaction of P2O4-7 with OH- did not occur instantly but over a wide range of temperatures. The d-HAP doped with NP would decrease the decomposition temperature of d-HAP. NP doped into d-HAP not only induced the d-HAP decomposition at lower temperature but also stabilized the βTCP crystal structure at higher-temperature. It could also increase the conversion temperature of βTCP to αTCP from 1180°C up to 1300°C. We could successfully prepare high-temperature (up to 1300°C) stabilized βTCP by heating NP doped d-HAP.