Preparation and Characterization of Apatite-Like Compound

Barium–lanthanum britholite solid solutions, Ba10-xLax(PO4)6-x(SiO4)xF2, with 0 ≤ x ≤ 6 were prepared by solid state reaction in the temperature range of 1200–1400 °C. The powders were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), F-selective electrode, X-ray diffraction (XRD), and Fourier transform infrared (FTIR). In addition, the present study used thermal analysis to follow the apatite formation reaction during the heat treatment. For x ≤ 3, there is formation of a single apatite phase, whereas above this value, the La2SiO5, La2Si2O7, BaSi2O5, and Ba2La2O5 secondary phases were observed. The variation of the lattice parameters of the apatite phase as a function of x confirmed that the solid solution is discontinuous to either side of x = 3.