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Cation Distribution and Non-Stoichiometry in MnCr2O4,-NiCr2O4 Spinel Solid-Solitions

  • C. Karataş
Part of the NATO ASI Series book series (ASIC, volume 276)

Abstract

Cation distribution in MnCr2O4.NiCrO4 spinel solid-solutions at 1300°C was calculated using non-linear disordering enthalpies obtained from the experimental cation distribution of Mn2+, Mn2+, Cr2+, Cr3+, Ni2+ and assuming random mixing on both tetrahedral and octahedral sites.The model also incorporates the electron exchange reaction:
$$M{n^{2 + }}C{r^{3 + }} = M{n^{3 + }} + C{r^{2 + }}$$
as well as site exchanges of newly formed cations. The Gibbs free energy of mixing derived from the available experimental data obtained in our.laboratory are discussed in conduction with the values calculated from the cation distribution model as the free energy of electron exchange reaction being a parameter. The effect of size mismatch of the substituting cations was taken into account using a solution model. Observed positive deviations from ideality suggests a miscibility gat, at lower temperatures.

Keywords

Free Energy Octahedral Site Tetrahedral Site Cation Distribution Configurational Entropy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • C. Karataş
    • 1
  1. 1.Hacettepe University-Nuclear Engineering DepartmentBeytepe, AnkaraTurkey

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