Atomic Resolution Studies of Tilt Grain Boundaries in NiO

摘要

The atomic structures of a number of <001> high-angle tilt grain boundaries in NiO bicrystals have been studied by high-resolution electron microscopy (HREM). Crystallinity is always maintained right up to the grain boundary (GB). Grain boundary planes bounded by a (100)-plane are preferred; however, symmetrical facets are also found at each misorientation. A tendency to match atomic planes across the GB is not only observed in symmetrical, but also in asymmetrical, GBs. Structural units can be clearly recognized in symmetrical GBs. Contrast differences suggest that a multiplicity of structural units exists for some GB configurations. Frequently symmetric GBs also show deviations from mirror symmetry. Multislice image simulations indicate that the Fresnel-like contrast associated with HREM GB images is not particularly sensitive to GB relaxation. (ERA citation 12:018600)