SURFACE-STRUCTURE OF CUBIC ALUMINUM-OXIDE

Molecular-dynamics simulations using a Pauling type pairwise potential have been carried out in order to study the structure of the surface of gamma-Al2O3. Starting from an ideal (100) face, a reconstruction pr ocess occurs in which the unbalanced coordination of surface ions tend s to fulfill their coordination capabilities. Oxygen ions come to the surface and pore formation with a concomitant increase of apparent vol ume takes place. The structure of the surface of the resulting materia l corresponds to a porous amorphouslike phase in which only short-rang e order is present. Analysis of the radial distribution function agree s with experimental x-ray-diffraction data.