A comprehensive study of the heat capacity of CsF from T= 5 K to T= 1400 K

In this study, we present new experimental heat capacity data of solid and liquid phase of CsF covering the temperature range from 5 K to 1400 K. The low temperature data were obtained by adiabatic calorimetry and compared with the theoretical heat capacity computed from ab initio harmonic crystal approximation. The absolute entropy at T = 298.15 K determined based on the presented results is 93.60 J · K - 1 · mol - 1 . The high temperature heat capacity was measured using a drop calorimeter and the data for the solid phase revealed significant excess properties. The data for the liquid phase were correlated with the molecular dynamic simulation obtaining a good agreement. The recommended molar heat capacity of the CsF solid phase is: C p , m ( J · K - 1 · mol - 1 ) = 24.291 + 6.4607 · 10 - 2 · ( T / K ) + 589981 · ( T / K ) - 2 J · K - 1 · mol - 1 and the one of the liquid phase was determined as: C p , m = 70.56 J · K - 1 · mol - 1 . From the calorimetric results the enthalpy of fusion of CsF was determined as: △ fus H = 22.1 ± 2.0 kJ · mol - 1 .