Enhancement of the 77 K irreversibility field and critical current density of (Bi,Pb)(2)Sr2Ca2Cu3Ox tapes by manipulation of the final cooling rate

By manipulating the cooling rate from the final heat treatment, we have raised the 77 K, self-field critical current density (J(c)) of multifilament (Bi,Pb)(2)Sr2Ca2Cu3Ox (2223) tapes by a factor of 3, and the irreversibility field (H*) by more than 50%. The J(c) of samples cooled in 7.5% O-2 from their reaction temperature of 825 degrees C increased from similar to 8 to similar to 24 kA/cm(2) and H*(77 K) increased from similar to 120 to similar to 200 mT as the cooling rate was decreased from 5 to 0.016 degrees C/min. The results unambiguously show that the flux pinning properties of 2223 tapes can be improved by simple changes in wire processing. (C) 1996 American Institute of Physics.