Crystal defects and critical currents in YBa2Cu3Ox

Abstract

Transmission electron microscopy data of crystal defects have been taken in as-sintered and zone-melted YBa2Cu3Ox samples to correlate with the corresponding critical current density properties. The origins and microstructural characteristics of the typical defects, including twin boundaries, grain boundaries, precipitates and dislocations are discussed. A new model is proposed to interpret the effect of twinning on the transport current density. High resolution electron microscopy data of dislocations observed in the zone-melted sample are presented, which indicate the possibility of these dislocations acting as strong pinning centers. Also discussed are the effects of these microstructural changes on transport and magnetization critical current density.