Synthesis, Crystal Structure, and High-Temperature Heat Capacity of Pb10 –xSmx(GeO4)2 +x(VO4)4 –x (x = 0.2, 0.5, 0.7, 1.0) Apatites from 350 to 1000 K

Pb_{10 –x}Sm_x(GeO₄)_{2 +x}(VO₄)_{4 –x} (x = 0.2, 0.5, 0.7, 1.0) compounds with the apatite structure have been synthesized by firing appropriate mixtures of the PbO, Sm₂O₃, GeO₂, and V₂O₅ oxides in air at temperatures from 773 to 1073 K. Their crystal structure has been studied using X-ray diffraction, and their high-temperature heat capacity (350–1000 K) has been determined by differential scanning calorimetry. The data have been used to evaluate their thermodynamic properties. [ABSTRACT FROM AUTHOR]