Thermodynamic Properties of Lanthanum-Gadolinium Zirconate Solid Solution

The molar heat capacity measurements were performed on the synthesized and characterized by X-ray diffraction and electron microscopy LaGdZr2O7 sample of the pyrochlore structural type in the temperature range of 2–1800 K. A heat capacity anomaly associated with a magnetic transformation in the range of 0–25 K was detected. The thermodynamic functions, such as smoothed heat capacity, entropy, enthalpy increment, and reduced Gibbs energy, were calculated. It was found that if the formation of the solid solution occurs with a change in the crystal structure of the binary oxides, the excess entropy exceeds the calculated value for ideal solutions, whereas with the preservation of the original structure, the entropy of mixing is almost equal to the value for an ideal solution.