Properties of Li-doped, polycrystalline, melt-textured, BiSrCaCuO tapes prepared by powder-in-tube processing

The effects of Li on Ag-sheathed Bi₂Sr₂CaCu₂O_8+x tapes have been studied by considering Li substitutions for Sr and Cu and Li additions to stoichiometric Bi₂Sr₂CaCu₂O_8+x. The materials were prepared by the powder-in-tube method. As the Li substitution reduces the melting temperature by as much as 160 K, careful control of the processing conditions is required to obtain superconductivity in Li-doped samples. Here we report on the effects upon J_c(B,T) and upon T_c. J_c(B) at 4.2 K and 20 K are reported. Due to a lack of phase purity, Li reduced the overall J_c of the tapes. At 20 K, however, the Li-doped material is much less dependent upon B, indicating that Li substitution may provide enhanced pinning at high field.