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 93.60J·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:Cp,m(J·K-1·mol-1)=24.291+6.4607·10-2·(T/K)+589981·(T/K)-2J·K-1·mol-1and the one of the liquid phase was determined as:Cp,m=70.56J·K-1·mol-1.From the calorimetric results the enthalpy of fusion of CsF was determined as:△fusH=22.1±2.0kJ·mol-1.

► The heat capacity of CsF was measured from 5 to 1400 K by two calorimetric techniques. ► The low temperature data were calculated by Phonon spectra. ► The heat capacity of the liquid phase was simulated by molecular dynamics. ► The measurement revealed significant excess heat capacity of the CsF.