Computer modelling techniques were used to investigate the defect and O transport properties of the Aurivillius phase Bi4Ti3O12. A range of cation dopant substitutions was considered including the incorporation of trivalent ions (M3+ = Al, Ga and In). The substitution of In3+ into the Bi site in the [Bi2O2] layer was predicted to be the most favourable. The calculations suggested that lanthanide (Ln3+) doping at the dilute limit occurred preferentially in the [Bi2O2] layer, with probable distribution over both the [Bi2O2] and the perovskite A-site at higher dopant levels. It was predicted that the reduction process involving Ti3+ and O vacancy formation was energetically favourable. The energetics of oxide vacancy migration between various O sites in the structure were investigated.

Defect and Dopant Properties of the Aurivillius Phase, Bi4Ti3O12. A.Snedden, P.Lightfoot, T.Dinges, M.S.Islam: Journal of Solid State Chemistry, 2004, 177[10], 3660-5