Defect structure of grain boundaries in Ba2YuC3O(7-x)

Correlations between observed defect structures and the orientation of planes involved in grain boundary (GB) formation in single phase, near ideal density orthorhombic Ba2YuC3O(7-x) are presented. Coherent boundaries involving only a low energy network of dislocations at the interface are associated with boundaries not involving the (001) basal plane, while basal-plane-faced GBs are highly defective. These results are interpreted using a model for local stress based on the known anisotropic thermal contraction of the material during cooling from sintering temperatures. Scanning Auger microscopy of in situ fractured surfaces demonstrates that there is preferential segregation of carbon at the GBs as well. 13 references