The thermodynamic properties of crystalline pentasodium hafnium tris(phosphate)

Abstract

The temperature dependence of the heat capacity of crystalline pentasodium hafnium tris(phosphate) was studied over the temperature range 6–650 K. The experimental data were used to calculate the thermodynamic functions of Na5Hf(PO4)3 from 0 to 650 K and the fractal dimension at 20–50 K. The standard entropy of formation from simple substances at 298.15 K was calculated from the absolute entropy value. The thermodynamic properties of Na5M(PO4)3 (M = Ti, Zr, and Hf) phosphates were compared.