Polycrystalline melt-textured samples which had been fabricated by using the liquid-phase removal method were analyzed by means of transmission electron microscopy. The samples contained a number of grains which were separated by high-angle grain boundaries with lengths of up to several mm. In order to determine the misorientation of the high-angle boundaries over large distances, an investigation was made of the effects of intragrain features upon the misorientations of the high-angle boundaries. The intragrain features included platelet boundaries and low-angle grain boundaries. The platelet boundaries were associated with parallel low-angle grain boundaries. The misorientation angles for the platelet boundaries were estimated to range from 0.5 to 5º, whereas the low-angle boundaries could have misorientation angles of up to 8º. Measurements of adjacent platelets showed that the misorientation between 2 points in the bulk was due to an alternation of the misorientation direction, and did not exceed 6º. The a-b plane alignment within the grain was maintained in this way. The misalignment of the a-b plane did not exceed 0.5º, and the misalignment of the a-b planes within the grain was due mainly to the out of a-b plane component, which could be up to 3.5º. The presence of platelet boundaries and low-angle grain boundaries affected the misorientation of a high-angle grain boundary and thus the current-carrying capability of the boundary. The misorientation over the entire length of the boundary was estimated and, for the high-angle grain boundaries, the variation in misorientation did not exceed 6º.

Determination of High-Angle Grain-Boundary Misorientations in Melt-Textured Y-Ba-Cu-O using Transmission Electron Microscopy Studies of Intragrain Structure. M.Mironova, G.Du, S.Sathyamurthy, K.Salama: Philosophical Magazine A, 1999, 79[5], 1079-94