$(Bi_0.7Pb_0.3)Sr_1Ca_1Cu_1.8O_x$ thick films were prepared by screen printing and sintering method. X-ary powder diffraction patterns, microstructures using a scanning electron microscope(SEM) and energy dispersive spectroscopy(EDS) data were taken to analyse phase transition, microstructure and the composition of phases respectively. Electrical properties have been investigate by 4-point probe method.
Various substrates were used for the deposition of $(Bi_0.7Pb_0.3)Sr_1Ca_1Cu_1.8 O_x$ thick films to study the effects of the substrates. Yttrium stabilized zirconia(YSZ) and alumina substrates interact strongly with the oxide resulting in poor superconductor, while silver and magnesia substrates are satisfactory to make screenprinted superconductors.
$(Bi_0.7Pb_0.3)Sr_1Ca_1Cu_1.8O_x$ thick films printed on magnesia substrate were sintered for 168h at various temperatures. The amount of the high -$T_c$ phase and the porosity of microstructure increase and the amount of the low-$T_c$ phase decreases with an increase in sintering temperature up to 850℃, but the trends reverse when the sintered above 850℃. Thus 850℃ is the most proper sintering temperature to form the high-$T_c$ phase. The amount of $Ca_2PbO_4$ decreases continuously with an increase in sintering temperature. As the sintering period increases, the amount of the high-$T_c$ phase increases, and the low-$T_c$ phase decreases. Transition temperature of the sample sintered at 850℃ for 216h appears to be 103K.
The rate of the formation of the high-$T_c$ phase was further increased by a resintering method. The $(Bi_0.7Pb_0.3)Sr_1Ca_1Cu_1.8O_x$ thick film which was sintered at 850℃ for 48h and resintered at 860℃ for 24h result in a superconductor with $T_c,extrapolation$ of 106K but with $T_c,zero$ of 86K.
The $(Bi_0.7Pb_0.3)Sr_1Ca_1Cu_1.8O_x$ thick films screen-printed on Ag substrate and sintered at 850℃ for 168h show that the amount of the high-$T_c$ phase is ~70%. The application of a cold rolling process causes an increase in the critical current density, $J_c$, and $J_c$ of ~3300A/㎠ and grain alignment of the thick film were obtained by the application of a cold rolling process.
