THERMODYNAMIC PROPERTIES AND CATION DISTRIBUTION OF THE ZNFE2O4-FE3O4 SPINEL SOLID-SOLUTIONS AT 900-DEGREES-C

The thermodynamic properties of the Fe3O4ZnFe2O4 spinel solid solution were determined at 900°C by the use of the solid electrolyte galvanic cell Fe2O3 + Fe3O4|O2-|Fe2O3 + ZnxFe3-xO4. The activity values obtained exhibit slight negative deviation from the ideal solution model. An analysis of the free energy of mixing of the spinel solid solution provided information on the distribution of cations between the tetrahedral and octahedral sites of the spinel lattice. This is the basis for the estimation of the free energy of formation of pure zinc ferrite from oxides. ΔG0ZnFe = -2740 - 1.6 T cal mole-1. © 1979.