As-prepared and uniaxially deformed melt-textured superconductors were used to determine the role that was played by dislocations in flux pinning. These superconductors were subjected to a high-temperature annealing process. It was found that, after annealing, the critical current density of as-prepared or of deformed superconductors had decreased markedly under zero field conditions as well as within an applied field of 1.5T. The distinctive characteristic of deformed superconductors, that the critical current density for a field oriented parallel to the c-axis was almost the same as that for a field which was parallel to the a-b plane, completely disappeared after annealing (900C, 48h, flowing O). Transmission electron microscopy revealed that the high dislocation density that was normally observed in deformed superconductors of this type had been significantly reduced. The results indicated that the large number of dislocations which was generated during deformation represented effective flux-pinning centers. It was suggested that pinning by stacking faults was magnetically sensitive, and the effect was greatest at low field strengths.

Y.Zhang, M.Mironova, D.F.Lee, K.Salama: Japanese Journal of Applied Physics, 1995, 34[I-6A], 3077-81