Direct identification of extended defects as vortex pinning centers in melt textured YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ composites

摘要

Single domain YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ melt textured ceramic composites have revealed a very rich microstructure, which has usually impeded, by using standard measurements, to evaluate the contribution of each defect to the enhancement of the critical current. We have measured the in-plane magnetoresistance anisotropy and the anisotropic in-plane inductive critical currents and we show that together with the microstructural TEM analysis, the contribution of the different extended pinning centers can be separated. These results have allowed us to infer the kind of microstructure modifications required to improve the critical current. In particular, we present an isostatic pressing deformation technique as a very promising post-processing treatment to strongly increase the critical currents of these composites.