Synthesis of Ag-Sheathed (Bi,Pb)-2223 Tapes Using the Precursor of (Bi,Pb)_2CuO_4+(Sr,Ca)_2CuO_3

摘要

A new process of the synthesis of superconducting (Bi,Pb)-2223/Ag tapes by the powder-in -tube (PIT) process is described. Two precursor powders are used, one is the (Bi,Pb)_2CuO_4 phase and the other is a multiphase with an approximate overall composition SrCaCuO_3. Using these precursor mixtures, we obtain the tapes with high density and wellaligned grains, and critical current densities (Jc) in the range of 6,000-10,000A/cm~2 at 77K in self-field. The good results are likely to be related to the presence of a liquid phase existed during sintering. The liquid phase creates favorable thermodynamic and kinetic condition during sintering, and result in the high density and well-aligned grains. However an amorphous phase is formed at the grain boundaries during the solidification of the liquid, which would strongly reduce the Jc.