Thermodynamic properties of zircon-manganite Lanthanum and Lithium LaLi2 ZrMnO6

The temperature dependence of the heat capacity of lanthanum and lithium zirconmanganite LаLi2ZrMnO6 was studied by the method of experimental dynamic calorimetry in the range of 298.15- 673 K. On the curve of the dependence Ср°~f(Т) at 348 K, a λ-shaped effect wasrevealed, probably related to a type II phase transition. Taking into account the temperature of the phase transition, the equations of the temperature dependence of the heat capacity of zirconmanganite are derived. The calculated value of the standard heat capacity of lanthanum and lithium zircono-manganite is in satisfactory agreement with experimental data within the error limits of experimental and computational methods. The standard entropy of the investigated zircono-manganites is calculated by the method of ion increments. In the range 298.15-673 K, the temperature dependences Ср°(Т) and the thermodynamic functions S°(T), H°(T)-H°(298.15) and Fxx(Т) were calculated. According to the developed methodology, the fundamental thermodynamic constant, the standard enthalpy of formation of zircono-manganite LаLi2ZrMnO6,was calculated.