Thermodynamics of PrPO4 whiskers

The heat capacity of PrPO4 whiskers, up to 1000-1500 nm in length and 45 ± 15 nm in diameter, was measured in the temperature range 1.93-1173.2 K. The heat capacity was measured by three methods: in the low temperature region by relaxation and adiabatic methods, and in the high temperature region by the DSC method. Based on the data obtained, values of thermodynamic functions were calculated. The heat capacity of a PrPO4 sample with isometric particles was measured in the range 325.2-1173.2 K. A comparative analysis of the thermodynamic data and IR spectra for samples with different particle habits was carried out. The influence of morphology on the enthalpy and entropy contributions to the total energy of the system was estimated. According to these data, the predominance of the entropy contribution raises the thermodynamic stability of the PrPO4 structure with whisker particles as the temperature rises.