Low temperature heat capacities and thermodynamic properties of rare earth triisothiocyanate hydrates——Pr（NCS）₃· 7H₂O and Nd（NCS）₃· 7H₂O

摘要

Heat capacities of Pr(NCS)3·7H2O and Nd(NCS)3· 7H2O haw been measured from 13 to 300 K by using a fully automated adiabatic calorimeter. Schottky anomaly was observed for Pr(NCS)3·7H2O below 50 K. The polynomial equations for calculating the heat capacity values of the two compounds in the range of 13-300 K were obtained by the least-squares fitting based on the experimental Cp data. The Cp values below 13 K were estimated by using the Debye-Einstein and Schottky heat capacity functions. The standard molar thermodynamic functions were computed from 0 to 300 K. The standard entropies and Gibbs energies of formation of the two compounds were also calculated.