Preparation of dense, high JC Bi-2223 superconductors by multistage cold pressing

The effect of multistage cold uniaxial pressing on Bi-2223 bulk superconductors with varying fractions of Bi-2223 in the precursor powder has been studied. The results show that the final density, grain orientation, J(C) and J(C)-B characteristics depend greatly on the fraction of Bi-2223 contained in the precursor and increase with increasing Bi-2223 fraction. In a three-stage repeated press-sinter schedule, density and J(C) (77 K) values as high as 5.76 g cm(-3) and 3110 A cm(-2) respectively could be achieved with 80% Bi-2223 precursor, whereas the values are only 5.31 g cm(-3) and 1860 A cm(-2) for 22% Bi-2223 precursor under identical conditions. The likely reasons for the wide variation of microstructural and superconducting properties are discussed.