Disorder in stoichiometric magnesioferrite, MgFe2O4, was determined from in situ synchrotron powder X-ray diffraction data [λ = 0.3738(4) Å] at 6, 5, and 3 GPa and temperatures up to 1430 K. The a unit-cell parameter increases linearly on heating at the three different pressures. Higher pressures cause a smaller cell volume, as expected. Cation order was analyzed in terms of the inversion parameter, x, {iv[Mg1−xFex]vi[Mgx/2Fe1−x/2]2O4} and the order parameter Q = 1 − (3/2)x. As pressure increases, the inversion parameter increases in inverse MgFe2O4 spinel. O’Neill and Navrotsky (1983) and Landau models were used to describe the equilibrium non-convergent ordering process in MgFe2O4, and they both fit the data well.

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