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Pore-structure stability of pure and Ce-doped alumina in air and argon atmospheres was studied using DTA, TGA, N 2 ads./des, and XRD with a view to understand the importance of the ionic size of the dopant cation on the porestructure stability of alumina. The ionic size effect was studied by heat treating the Ce-alumina system in both oxidizing and reducing atmospheres to have Ce 4÷ (87 pm) and Ce 3÷ (106 pm) respectively. No compound formation between Ce and alumina was observed. In the case of pure alumina there is a drastic reduction in porosity during the transformation to e-alumina. Ce-doped alumina has a higher DSC transformation temperature corresponding to the (~-alumina transformation compared to pure alumina. Ce-doped alumina showed higher pore-structure stability compared with pure alumina and the stability was relatively higher in reducing atmosphere (higher Ce3÷/Ce 4÷ ratio, higher effective ionic size) compared with oxidizing conditions (lower Ce3+/Ce 4÷ ratio, lower effective ionic size).

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