CALCULATED STRUCTURES AND ENERGIES OF GRAIN-BOUNDARIES IN ALPHA-AL2O3

Static-lattice calculations of the energies and structures of (10 $$($) over bar 1n) (n = 0, 1, and 4) and (0001) grain boundaries in alpha-Al2O3 using three different potentials are reported. It was found that the energies of boundaries perpendicular to the (0001) direction vary between 0.3 and 0.9 J.m(-2). These compare favorably to experimental values, and the results are not sensitive to the choice of potential. The energies of the other boundaries do depend on the potential, but their relaxed structures do not. Using the most reliable potential, the energies of boundaries which have been studied by high-resolution electron microscopy range from 1.0 to 1.7 J.m(-2) Simulated images of the calculated structures compare favorably with high-resolution electron microscope micrographs of these boundaries.