TEM STUDIES OF DISLOCATIONS IN DEFORMED MELT-TEXTURED YBA2CU3OX SUPERCONDUCTORS

TEM studies have been conducted on melt-textured YBa2Cu3Ox samples tha t were uniaxially and isostatically deformed at high temperatures and compared with those of undeformed samples. Dislocation pile-ups along [100] and [010] are found to be the common feature between undeformed samples with the best J(c) and the uniaxially deformed samples, and ar e suggested to be responsible for enhanced pinning when the magnetic f ield (H) is applied parallel to the a-b plane. Dislocation loops, tang les, and arrays are also observed, and are considered to contribute to pinning in field orientations other than H parallel-to a-b. In additi on to these dislocations, [301] type partial dislocations are found to be present in isostatically deformed samples. The strain field around these dislocations is considered to be an additional source of pinnin g in the intermediate field orientations.