Distribution of tetrahedral and octahedral A1 sites in gamma alumina

Experimental and computational studies of γ-Al2O3 show that 70±2% of Al ions occupy octahedral interstitial sites in the fcc oxygen structure, and the rest tetrahedral sites. The experimental data come from 27Al MAS NMR and the theoretical results from ab initio quantum mechanical energy calculations for nine superlattice structures, analysed to extract various parameters which were then fed into a Monte Carlo simulation of the γ-Al2O3 structure. The simulation throws new light on the reasons for the structural disorder.