SEGREGATION OF MAGNESIUM TO THE INTERNAL SURFACE OF RESIDUAL PORES IN TRANSLUCENT POLYCRYSTALLINE ALUMINA

For the first time direct evidence for Mg segregation to the surface of pores within translucent polycrystalline alumina grains has been found using energy dispersive X-ray spectroscopy (EDXS) and convergent beam electron diffraction (CBED) in an analytical electron microscope (AEM) on a submicrometer scale. This supports the model that MgO dopant increases the surface diffusivity which, in turn, increases the pore mobility. The MgO dopant's role in retarding grain growth in combination with the enhanced pore mobility allows the achievement of nearly full density and translucency in alumina.