ENHANCEMENT OF TEXTURE AND CRITICAL CURRENT DENSITY IN Bi_2Sr_2Ca_1Cu_2O_8 SUPERCONDUCTING TAPES THROUGH MAGNETIC FIELD PROCESSING

摘要

Ag-sheathed Bi-2212 tapes with varying core thickness were heat treated in flowing O_2 in magnetic fields up to 15 T. A uniform, high-degree of texture is achieved throughout the thickness of the tapes when heat treated in a magnetic field, whereas a large portion of non-textured region exists without magnetic field. The critical current density J_c of the tapes increases with increasing field strength due to enhancement in texture. The self field critical current I_c > 1000 A is achieved for tapes with a core thickness of 180 μm. For tapes with larger core thicknesses, however, I_c decreases due to inhomogeneous melting. The magnetic field is more effective in enhancing texture in the early stages of crystal growth.