Observation on microstructures of YBCO superconductor by powder melt process

The bulk YBa2Cu3Ox superconductors (YBCO) fabricated by a new melt approach, open-quotes Powder Melt Processclose quotes (PMP), have a very high Jc(B) values which exceed 71000 A/cm2 at 77 K, 1 T and 36000 A/cm2 at 77 K, 4 T. SEM and TEM revealed that the microstructures of PMP samples have characteristics especially beneficial to Jc-B: extremely thin layer grains, clean discontinuous low angle grain boundary, fine and dispersive 211 particles, high dense crystal defects and the more effective suppression of crack formation. It was found that Jc values of PMP samples increase as the spacing of 211 particles decreases. The flux pinning centers and origin of microstructure formation are discussed