EVALUATION OF ATOMIC GRAIN-BOUNDARY STRUCTURE IN ALUMINA BY MOLECULAR-ORBITAL METHOD

The atomic structure of symmetrical Sigma 7[0 (1) over bar 11]/180 deg rees grain boundary in alumina was evaluated by DV-Xa molecular orbita l method. By using a (Al2O10)(14-) cluster model, surrounded by Mardel lung potential, bond overlap population (BOP) and net charge (NC) at t he grain boundary were evaluated as a function of the interplanar spac ing between two adjacent grains across the grain boundary. BOP and Cou lomb's force calculated from NC were maximized by taking the interplan ar spacing as approximately 0.13 nm, This result agrees well with the interpretation of atomic grain boundary structure obtained from high r esolution electron microscopy (HREM) analysis.