Critical current density and microstructures of thick monocore Bi2212 tapes grown in high magnetic fields

Abstract

Ag-sheathed Bi2212 monocore tapes with core thickness between 80 and 700 /spl mu/m were heat-treated in flowing O/sub 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 (H/sub a/) whereas a large portion of nontextured region exists without magnetic field. The critical current density J/sub c/ of the tapes increases with increasing H/sub a/ due to enhancement in texture. The self field critical I/sub c/>1000 A was achieved for tapes with a core thickness of 180 /spl mu/m. However, for tapes with larger core thicknesses, I/sub c/ decreases due to inhomogeneous melting. The magnetic field is more effective in enhancing texture in the early stages of crystal growth.