Surface Segregation and Morphology of Mg-Doped α-Alumina Powders

摘要

This work considers the effect of a thermal treatment, at a temperature equal to or higher than 1200℃, on the physical and chemical characteristics of submicron α-alumina powders, doped with 550 and 1650 ppm in weight of MgO. The powders have been characterized by TEM, SEM, BET, XPS and chemical analysis. TEM observations show that the grains have elongated and rounded forms and exhibit considerable agglomeration. The BET surface area of the powder decreases with increasing annealing time and temperature and increases with the amount of MgO. XPS analysis shows a strong segregation of Mg and this effect is more pronounced when the size of the grains increase. In some cases XPS also detected the presence of Na, Ca and Si in the surface region of the grains.