Synthesis, Crystal Structure and Thermodynamic Properties of Apatite-like Lead Gadolinium Vanadato-germanates

Abstract

The Pb10-xGdx(GeO4)2+x(VO4)4-x (x = 0.5, 1.0) apatites were synthesized by the solid-phase synthesis by roasting stoichiometric mixtures of PbO, Gd2O3, GeO2, and V2O5 in air at temperatures of 773–1073 K. Their crystal structure was determined using X‑ray diffraction analysis. The high-temperature heat capacity (350–1000 K) was measured by differential scanning calorimetry. The experimental data Cp = f (T) were used to calculate the thermodynamic properties of apatites