Calorimetry of new double dysprosium tellurite

Abstract

New dysprosium-barium double tellurite was synthesized based on ceramic technology. The formation of the equilibrium composition of the compound is controlled by X-ray phase analysis, the results of which revealed that DyBaTeO4.5 dysprosium tellurite was synthesized. For the first time, a calorimetric study of the heat capacity of the new double tellurite DyBaTeO4.5 was carried out in the temperature range of 298.15–673 K. The calibration of the instrument was carried out on the basis of the determination of the heat meter thermal conductivity. The operation of the calorimeter was checked by measuring the α-Al2O3 heat capacity. The experimental data of the specific and molar heat capacity were processed by the methods of mathematical statistics. The equation for the dependence Cpo~f (T) is derived based on the experimental data. The temperature dependences of the thermodynamic functions Ho(T)–Ho(298.15), So(Т) and, Fхх(Т) are determined from Cpo~f (T) and the calculated value of So(298.15) of tellurite. Anomalous jumps are observed on the dependence Cpo~f (T), which are probably related to second-order phase transitions. The thermodynamic characteristics of new tellurite can serve as background information for fundamental data banks and reference books, and also used to predict the thermochemical constants of similar compounds.