Heat Capacity and Thermodynamic Properties of Germanates CaGd2Ge4O12 and CaDy2Ge4O12 in the Range of 320–1000 K

The germanates CaGd2Ge4O12 and CaDy2Ge4O12 were synthesized from CaO, Gd2O3 (Dy2O3), and GeO2 by the standard ceramic technology. Their crystal structure was refined by X-ray diffraction analysis. The high-temperature heat capacity was measured in the temperature range 320–1000 K using differential scanning calorimetry. Their thermodynamic functions were calculated from the experimental dependences Cp = f(T).