The thermodynamic characteristics of NdBa2Cu3O7-δ

Dissolution enthalpies of the Nd2O3, BaCO3, CuO, NdBa2Cu3O7-δ are measured by means of dissolving calorimetry at 325.15 K. On the gained information the enthalpies of two different reactions with the participation of the NdBa2Cu3O7-δ [ΔrH Deg (323.15 K)] phase and formation enthalpies of the NdBa2Cu3O7-δ [ΔfH Deg (323.15 K)] are calculated from variable initial components including monoatomic gases. Specific heat (Cp Deg) of the NdBa2Cu3O6.98 sample are measured over the 100 - 320 K interval. Using obtained values of the Cp Deg the thermodynamic functions ΔrH Deg (T) and ΔfH Deg (T) are calculated on the range of 298.15 - 323.15 K. The compound NdBa2Cu3O6.98 was established to be thermodynamically fixed at the ratio 0.5Nd2O3 + CuO + 2BaCuO2 over the 298.15 - 323.15 K range. The values of Gibbs energies and entropies of the reaction involving phase Nd123 are given