Magnetite (Fe3O4) Heat capacity and thermodynamic properties from 5 to 350 K, low-temperature transition

Abstract

The heat capacity of synthetic Fe3O4 has been measured over the range from 5 to 350 K. Values of thermodynamic functions have been calculated and Cp, So, and (Ho - H0o)/T at 298.15 K are 36.04, 34.93, and 19.85 cal mol-1 K-1, respectively. In this sample the previously known [lambda]-type transition was found to consist of two maxima, a larger one at 118.9 K and a smaller one at 113.3 K, with entropy increments of 1.2 cal mol-1 K-1 and 0.2 cal mol-1 K-1, respectively. The mechanism of the transitions is discussed.