Initial sintering of oxide powders annealed at moderate temperatures corresponds to a surface area reduction or particle growth without increase in density and mechanical toughness of the material. Application of ultrafine oxide powders in the field of catalysis requires a good thermal stability. More often such materials do not exhibit the appropriate high surface area during a long period at temperatures in the range 800-1200 K. The decrease in surface area as a function of time has already been studies by several authors, as for example, in the case of MgO ,ZnO and transition alumina...