Abstract
Calorimetric research of a heat capacity of a triple lanthanum tellurite in the range of 298.15-673 КThis paper presents detailed results of new lanthanum tellurite synthesis and its heat capacity calorimetric research.For the first time, a triple lanthanum tellurite was synthesized by the solid-phase method from oxides of lanthanum, nickel (II), tellurium (IV) and calcium carbonate.The generation of the equilibrium composition of the synthesized compound was controlled by the method of X-ray diffraction analysis (XDA) on the diffractometer DRON-2.0.By the results of the XDA it was established that there was synthesized a triple lanthanum tellurite La 2 CaNiTeO 7 .Heat capacity at constant pressure of the synthesized tellurite was researched by the method of dynamic calorimetry at the range of 298.15-673К.Based on the experimental data, the equations, describing dependencies of heat capacity of the compound on temperature were calculated.When studying the temperature dependences of the heat capacity of La 2 CaNiTeO 7 , abnormally sharp λ-like peaks probably associated with second-order phase transitions, were observed at 423 K. Temperature dependencies of thermodynamic functions of La 2 CaNiTeO 7 Sº(T), Hº(T)-Hº(298,15), Ф хх (Т) were calculated based on the experimental data С р º(Т) and the calculated value Sº (298.15).