Heat capacities and derived thermodynamic functions of neodymium–gadolinium zirconates from 298.15 to 1050K

Abstract: X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize Nd x Gd2− x Zr2O7 (x =0, 0.6, 1.0, 1.4, and 2.0) solid solutions pressureless-sintered by using ceramic powders acquired by chemical-coprecipitation and calcination method. Heat capacity measurements were performed with a heat flux-type differential scanning calorimetry in the temperature range of 298.15–1050K. The heat capacity of Nd x Gd2− x Zr2O7 solid solutions increases with increasing the concentration x of neodymium cations from x =0 to x =2.0 at identical temperature levels. At 298.15K, the heat capacities of Nd0.6Gd1.4Zr2O7, NdGdZr2O7 and Nd1.4Gd0.6Zr2O7 are 217, 220 and 224JK−1 mol−1, respectively. Thermodynamic functions such as enthalpy increment, entropy and Gibbs energy functions were calculated from the measured heat capacity data. [Copyright &y& Elsevier]