TEM studies of dislocations in deformed melt-textured YBa2Cu3Ox superconductors

Abstract

TEM studies have been conducted on melt-textured YBa2Cu3Ox samples that 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 Jc and the uniaxially deformed samples, and are suggested to be responsible for enhanced pinning when the magnetic field (H) is applied parallel to the a-b plane. Dislocation loops, tangles, and arrays are also observed, and are considered to contribute to pinning in field orientations other than H ‖ a-b. In addition 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 pinning in the intermediate field orientations.