| Popis: |
The heat capacity of rubidium hexafluoroarsenate, RbAsF6, was measured from 300 to 700 K by differential scanning calorimetry. The results indicate that the structural transformation from the rhombohedral to the cubic phase occurs in the range 305–436 K through an intermediate stable phase and reaches isothermal completion in a narrow temperature range of 407–409 K. The enthalpy of the transformation is 10.90 ± 0.03 kJ/mol, and its entropy is 26.39 ± 0.08 J/(K mol) = Rln24, which suggests that this structural transition is of the order–disorder type. The heat capacity data are used to evaluate the thermodynamic properties of RbAsF6 in the range 300–700 K. |
