Heat Capacity and Thermal Expansion of Yttrium Tantalate

Abstract

The isobaric heat capacities of two monoclinic (M' and M) modifications of yttrium orthotantalate at temperatures 5–1300 K have been measured by the adiabatic and differential scanning calorimetry methods. It has been demonstrated that the difference in structure between the crystal lattices of M' and M has little effect in the heat capacity, and the difference between the heat capacities of these phases C_p(M) – C_p(M') is small, always positive, and increases in the range of the lowest temperatures. The unit cell parameters of M-YTaO₄ have been determined as a function of temperature in the range 300–1173 K.