Thermodynamic and spectroscopic properties of Co7/3Sb2/3O4

Highlights: • The temperature dependence of heat capacity of Co7/3Sb2/3O4 has been measured. • The experimental data were used to calculate standard thermodynamic functions. • Spectroscopic studies were carried out to study of the phase transition at T = 60.3 K. • The structure of Co7/3Sb2/3O4 is refined by the Rietveld method. • The high-temperature X-ray diffraction was used for determination phase transition. - Abstract: The temperature dependence of heat capacity of Co7/3Sb2/3O4 has been measured for the first time in the range from (6 to 337) K by precision adiabatic vacuum calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity, enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs function G°(T) − H°(0), for the range from T → (0 to 337) K. Additional spectroscopic studies were carried out to study the nature of the phase transition at T = 60.3 K. The structure of Co7/3Sb2/3O4 is refined by the Rietveld method: space group F d3m, Z = 8, a = 10.3793(2) Å, V = 1118.14(4) Å3. The high-temperature X-ray diffraction was used for the determination of temperature of high-temperature phase transition and coefficient of thermal expansion