Effect of Uniaxial Pressure on Powder Compaction of Bi,Pb-Sr-Ca-Cu-O Superconductor

The effects of uniaxial-press on the formation of the high-Tc phase in the Bi-Pb-Sr-Ca-Cu-O system studied through X-ray diffraction experiments, density measurements, SEM and DTA. Samples with a starting composition of Bi:Pb:Sr:Ca:Cu=0.96:0.24:1.0:1.1:1.6 was heated at 850°C for various period (1st-sintering), pressed uniaxially at 0.5 to 2.0 GPa, and heated at 850°C for 72h (2nd-sintering). Density increases as pressure increases and lst-sintering period extends. Volume fraction of the high-Tc phase after 2nd-sintering reaches high values but is independent of pressure for samples subjected to lst-sintering. Orientation ratio after 2nd-sintering, which is estimated from peak intensity ratio, decreases for lst-sintering periods ≦ 24h as pressure increases, while it increases and reaches high values for the period of 48h. The uniaxial-press is effective in high-denstisifacation, high-orientation and promotion of the formation of the high-Tc phase for samples heated at 850°C for 48h before press.