Structural and chemical analysis of well-crystallized hydroxyfluorapatites

X-ray diffraction (XRD) patterns of hydroxyfluorapatites with a nominal composition of Ca-10(PO4)(6)(OH)(2-x)F-x, where x = 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0, were collected and analyzed using the Rietveld method. A multiphase Rietveld analysis performed on calcined samples reveals a range of Ca/P ratios from 1.56 for the sample with x = 0.4 to 1.67 for the sample with x = 2.0 on the synthesized powders. Calcined apatites exhibit a decrease in the lattice parameter a, a greater crystallite size, lower distortion in the phosphate tetrahedra, and greater stability of the apatite structure for higher fluoride contents.