MICROSTRUCTURE AND SUPERCONDUCTING PROPERTIES OF PB-SUBSTITUTED BI2SR2CACU2OX AG DIP-COATED TAPES/

The microstructure and superconducting properties of Pb-substituted Bi -2212/Ag tapes fabricated by dip-coat techniques and melt-solidificati on process have been investigated. It is found that the transport crit ical current density is significantly decreased and the field dependen ce is increased by the Pb substitution in Bi-2212/Ag tapes, assigned t o the altered microstructure which is very sensitive to the atmosphere of melt-solidification process. No grain alignment is observed under processing in air or lower oxygen pressure, resulting in a poor grain connectivity and very low transport J(c). While, the aligned grains ar e formed along 2212/Ag interface during processing in pure oxygen and the grain coupling is improved with decreasing cooling rate, producing a high transport J(c). (C) 1998 Elsevier Science B.V.