Comparative study of Jc, flux pinning, and the influence of irradiation in Bi-2212 ribbon and single crystals

In the BiSrCaCuO (BSCCO) superconductors there has been considerable success in overcoming weak link problems, and at high temperatures intra-grain flux motion is thought to be the dominant dissipation mechanism. Polycrystalline BSCCO tapes have critical current densities (J(c)) at high temperatures that are large compared with those in BSCCO single crystals. In order to further improve J(c) in the tapes, it is essential to identify the additional flux pinning mechanisms in them. The microstructural and electrical homogeneity of Bi2Sr2CaCu2O8+d ribbon (Bi-2212/Ag) provides a good basis for comparison with of Bi-2212 single crystals, in order to investigate and highlight the pinning in polycrystalline ribbons. We report a detailed study on the effect of irradiation on J(c) in both Bi-2212 single crystals and Bi-2212/Ag ribbons using magnetisation measurements. Information regarding the intra-granular flux pinning of the grains within the ribbon has been obtained.