Low-temperature heat capacities and Verwey transition of magnetite

Heat capacities of stoichiometric magnetite crystals (Fe3O4) were measured by adiabatic calorimetry from T = 13 K to 300 K. The Verwey transition was observed as a single sharp anomaly at T = 123.82 K in the heat-capacity curve. The transition molar enthalpy ΔtrsHm and entropy ΔtrsSm including the tail portion extending from about T = 80 K to 230 K were estimated as 980.8 J·mol-1 and 7.67 J·K-1·mol-1, respectively. The thermodynamic properties of the transition are discussed. Several thermodynamic functions were calculated from the measured heat capacities and tabulated at round temperatures.