High-resolution transmission electron microscopy studies of a near SIGMA 11 grain boundary in alpha -alumina

Atomistic structure of near SIGMA 11 (N SIGMA 11) grain boundary in ultrapure alpha -Al sub 2 O sub 3 bicrystals was determined. High-resolution imaging revealed an atomically sharp interface with characteristic periodic pattern at (0 minus 111) parallel to (01 minus 11) facets. The pattern was analyzed by comparing the HRTEM micrographs with simulated images of different structures relaxed by static-lattice calculations. Best agreement with experiment was reached for the grain-boundary structure with the lowest energy (1.7 J center dot m sup - sup 2 ). Although this structure reproduced the relative translation state of the adjacent crystals to within 0.02 nm, the calculated structure was not in complete agreement with the periodic pattern at the grain boundary. 46 refs.