Synthesis, Structure, and Thermophysical Properties of EuGaGe2O7

The europium gallium germanate EuGaGe(2)O(7)has been prepared by solid-state reaction in air in the temperature range 1273-1473 K using a stoichiometric mixture of Eu2O3, Ga2O3, and GeO2. Its crystal structure has been determined by X-ray diffraction (sp. gr.P2(1)/c,a= 7.1693(7) angstrom,b= 6.57008(6) angstrom,c= 12.7699(1) angstrom, beta = 117.4522(5)degrees,V= 533.768(8) angstrom(3)). The heat capacity of polycrystalline samples has been determined by differential scanning calorimetry in the temperature range 350-1053 K and the experimental data have been used to calculate the thermodynamic properties (enthalpy increment, entropy change, and reduced Gibbs energy change) of EuGaGe2O7.