Heat Capacity and Thermodynamic Properties of β-Pyrochlore Complex Oxides RbTe1.5W0.5O6 and Rb0.95Nb1.375Mo0.625O5.79

Abstract

It was for the first time that the heat capacity of β-pyrochlore complex oxides RbTe_1.5W_0.5O₆ and Rb_0.95Nb_1.375Mo_0.625O_5.79 was investigated by adiabatic vacuum calorimetry and differential scanning calorimetry in the temperature range T = (6–640) K. The obtained experimental data were used to calculate the standard thermodynamic functions: heat capacity \(C_{{\text{p}}}^{o}\), enthalpy [H°(T)−H°(0)], absolute entropy [S°(T)], and Gibbs free energy [G°(T)−H°(0)] for the range from T → 0 to 640 K. The low-temperature (T < 50 K) heat capacity trends were analyzed in terms of the multifractal model, and a chain–layered structure topology of the studied compounds was established.