Cation distribution in binary oxides with spinel structure. A model quantum-chemical approach

A basis has been given for the use of the preference index E/sub pref/ for the normal (inverse) spinel structure for the case of binary oxides in the form of the difference between the single-cation indices /delta//(M/sup t+/)/ characterizing the favorability of the introduction of the cations into the tetrahedral positions (A), compared with the octahedral positions (B) of the spinel lattice. The indices /delta//(M/sup 2+/)/ were obtained by a quantum-chemical calculation for the A and B transition metal clusters with the localized boundary orbitals of the oxygen atoms directed toward the cation. For most 2-3 and 2-4 spinels, the calculated indiced E/sub pref/ correctly predict the cation distribution.