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 Sr 2 Ca 2 Cu 3 O x ͑2223͒ 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°C increased from ϳ8 to ϳ24 kA/cm 2 and H*͑77 K͒ increased from ϳ120 to ϳ200 mT as the cooling rate was decreased from 5 to 0.016°C/min. The results unambiguously show that the flux pinning properties of 2223 tapes can be improved by simple changes in wire processing. © 1996 American Institute of Physics. ͓S0003-6951͑96͒00145-3͔Improving the J c of 2223 superconductors in an applied magnetic field provides the most direct path to broad application of high-temperature superconductor ͑HTS͒ wire. Agclad 2223 made using the powder-in-tube process is currently the most promising HTS wire technology because established processes can be used to manufacture long lengths of strongly linked material. However, in contrast to Y-and Tl-based superconductors, 2223 has relatively weak flux pinning properties above about 30 K. For this reason, use of 2223 wires in moderate to high applied fields is currently limited to low temperature.Three strategies have been used previously to improve flux pinning in Bi-based superconductors. One successful approach has been postprocessing irradiation. 1 However, although the in-field transport J c can be significantly enhanced, it is not clear to what extent this method can be applied to practical wire manufacturing. A second approach has focused on introducing defects associated with dopants, dislocations, and particles. [2][3][4] While this has achieved some success, enhancements to the transport J c of HTS wires in an applied field has not yet occurred. Finally, controlled manipulation of the oxide constitution to produce impurity phase particles in Bi-2212 5 has met with limited success. In this contribution, we show that simple modifications to the heat treatment can enhance both the zero field and the infield properties of 2223 tapes.Parrell et al. 6 have shown that the rate at which 2223 tapes are cooled after heat treatment can have a large effect on the transport J c , critical temperature (T c ) transition, and filament microstructure. They reported that slow cooling ͑Ͻ0.1°C/min͒ in 7.5% O 2 increased the J c ͑77 K, self-field͒ by as much as 50% over tapes cooled more quickly, and considerably sharpened the T c transition, despite decomposition of the 2223 phase at temperatures below the 2223 phase stability limit. This letter builds on this previous work of Parrell et al. by exploring in detail one contribution to the J c improvement. In particular, we have evaluated the flux pinning contribution by measuring the cooling rate dependence of the irreversibility field, H*.Ag-clad 85-filament samples of nominal composition Bi 1.8 Pb 0.3 Sr 1.9 Ca 2.0 Cu 3.1 O x were processed to develop a dense and aligned 2223 phase structure. The final heat treatment...