Thermodynamic properties of nickel chromite (NiCr₂O₄) based on adiabatic calorimetry at low temperatures

Abstract

 The hitherto unknown low-temperature heat capacity of nickel chromite (NiCr₂O₄) was measured between 8 and 381 K using adiabatic calorimetry, and some thermochemical functions [C_P(T), S(T), S°₂₉₈, H_(T)−H₍₀₎] were derived from the results. The standard entropy (S°₂₉₈=140.0 ± 0.3 J mol⁻¹ K⁻¹) for nickel chromite was calculated from the results. Our calorimetric measurements indicate three major anomalies in the heat-capacity curve at temperatures between 8 and 381 K. A short literature review indicates that two of these anomalies can be accounted for, whereas an anomaly peaking at 29 K has not been reported previously.