Ic and phase characteristics of (Bi,Pb)2223 tapes after 1 heat treatment in a temperature gradient under different oxygen partial pressures

The heat treatment of (Bi,Pb)2223 tapes in a furnace with a temperature gradient allows the study of many heat treatment temperatures at the same time. 20 cm lengths of tape were given a typical first heat treatment of a period of 40 hours in a /spl sim/1/spl deg/C/cm temperature gradient under either 7.5% partial pressure O/sub 2/, or air. The maximum amount of (Bi,Pb)2223 occurred in a temperature window, (/spl les/2% change in the phase composition) of about 7/spl deg/C under 7.5% partial pressure and 2/spl deg/C under air. The relationship between the phase composition and the transport current, Ic, for both atmospheres is investigated.