The energetics of two macroscopic and nanosized spinel systems with magnetite end-member (Fe3O4-Fe8/3O4 and Fe3O4-Fe2TiO4) was studied using high temperature oxide melt solution calorimetry. The mixing properties of the solid solutions were obtained, and the effect of particle size on the thermodynamics was assessed. The surface energies of the nanosized materials were similar within the errors regardless of the composition, and were consistent with those determined for other spinels. The enthalpies of mixing in the titanomagnetite magnetite-maghemite solid solutions are also found to be similar at the macroscopic and nanoscale. The enthalpies and Gibbs energies of mixing of the macroscopic Fe3O4-Fe8/3O4 and Fe3O4-Fe2TiO4 systems were compared with the experimental results for two other inverse spinel solid solutions with magnetite end-member: Fe3O4 – Fe2MoO4 and Fe3O4 – NiFe2O4. The effect of the cation distribution, size mismatch and electron exchange reactions on the mixing thermodynamics was assessed and some systematic trends were observed.

Thermodynamics of mixing of spinel solid solutions with magnetite (Fe3O4) end-member Part II: Mixing of two inverse spinels

249th National Meeting (2015)

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