PROGRESS IN MELT TEXTURING OF YBA2CU3OX SUPERCONDUCTOR

Melt processing is the most prominent method utilized in the fabrication of bulk YBa2Cu3O(x)(123) because of the superior transport and magnetic properties of this material. Due to the Y-diffusion-controlled growth mechanism of 123, the maximum allowable growth rate is sensitive to the size and distribution of the Y2BaCuO5 precipitates. In addition, a slow cooling rate and a slow growth rate have to be employed to maintain the stability of the 123 planar growth front. Among the many melt-texturing methods and modifications, seeded directional solidification has the potential to produce long single-domained samples of large cross-sectional area with the strongly superconducting a-b planes aligned along the sample axis. Steady progress has also been achieved in flux-pinning enhancement through defect engineering. This includes the introduction and modification of defects such as twins, irradiation damage and second-phase inclusions. In particular, high-temperature mechanical deformation has been shown to be effective in increasing the dislocation density and results in improved J(c) as well as reduced J(c) anisotropy.