Thermodynamic functions of eskolaite Cr2O3(c) at 0–1800 K

Abstract

The heat capacity of eskolaite Cr2O3(c) was determined by adiabatic vacuum calorimetry at 11.99–355.83 K and by differential calorimetry at 320–480 K. Experimental data of the authors and data compiled from the literature were applied to calculate the heat capacity, entropy, and the enthalpy change of Cr2O3 within the temperature range of 0–1800 K. These functions have the following values at 298.15 K: Cp0 (298.15) = 121.5 ± 0.2 J K−1mol−1, S0(298.15) = 80.95 ± 0.14 J K−1mol−1, and H0(298.15)-H0(0) = 15.30±0.02 kJ mol−1. Data were obtained on the transitions from the antiferromagnetic to paramagnetic states at 228–457 K; it was determined that this transition has the following parameters: Neel temperature TN = 307 K, ΔtrS = 6.11 ± 0.12 J K−1mol−1 and δtrH = 1.87 ± 0.04 kJ mol−1.