Theoretical explanation of the uniform compressibility behavior observed in oxide spinels
نویسندگان
چکیده
Simple algebraic equations show that the bulk compressibility in spinel-type compounds can be expressed by means of cation oxide polyhedral compressibilities and a term that accounts for the pressure effect on the internal oxygen position in the unit cell. The equations explain ~i! the difference of compressibilities at octahedral and tetrahedral sites, ~ii! why the macroscopic bulk modulus can be estimated as the average of these polyhedral bulk moduli, and ~iii! the uniform behavior found in oxide spinels under hydrostatic pressure. Quantum-mechanical ab initio perturbed ion results on MgAl2O4 , ZnAl2O4 , ZnGa2O4, and MgGa2O4 direct spinels and on MgGa2O4 inverse spinel are reported to illustrate the interpretative capabilities of the proposed equations.
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