Vertical magnetic fields up to 15 T were applied to the magnetic melt-processing (MMP) of Bi2212 bulks and Ag-sheathed tapes with a core thickness above 80 μm, which were set horizontally. Texture with the c-axis along the direction of magnetic field applied during MMP is developed due to the anisotropy in magnetic susceptibility of Bi2212. The degree of texture and the anisotropy factor in magnetization increase almost linearly as the magnetic field strength Ha during MMP is increased. The anisotropy factor in magnetization reaches 6.5 at a Ha of 13 T for Ag-doped Bi2212 bulks, whereas for Bi(Pb)2212 in which Pb partially substitutes for Bi the factor is suppressed to a half of that of Ag-doped Bi2212. The transport critical current Ic and the critical current density Jc of Bi2212 tapes also increase with increasing Ha due to the texture development and Ic reaches above 1000 A in self-filed for the tapes with a core thickness of 180 μm. However, for further thicker tapes, Ic decreases. The suppressions in the Ic for the tapes and in the anisotropy factor in magnetization for Bi(Pb)2212 bulks are due to inhomogeneous melting, and inhomogeneous nucleation and growth of crystals during MMP. When crystal growth is restricted, crystal alignment is suppressed.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering