Computer simulation, using an ionic, Born-like model, is used to investigate the accommodation of titanium impurities in Ca-Al-Fe-O phases. Specifically, calcium titanate solution in Al2O3, Fe2O3, CF, C2F, CA, C(2)A, C(3)A, and C(4)AF (where C denotes CaO) is considered. The simulations predict that titanium impurities are found preferentially in the ferrite phases. At sufficiently high concentrations, the solution involves the formation of clusters containing 3 to 6 ions that strongly resemble the structure of the calcium titanate phase. The calculations reveal that the compensation mechanism varies appreciably over the range of compounds considered. (C) 2000 Kluwer Academic Publishers.