Influence of the synthesis conditions on the phase formation and superconducting properties of Bi_1.6Pb_0.4Sr_2-xK_xCa₂Cu₃F_0.8O_y ceramics

The influence of the synthesis temperature and the time on the phase formation, critical current density (J_c), critical temperature (T_c) and the normal state resistivity (ρ) of Bi_1.6Pb_0.4Sr_2-xK_xCa₂Cu₃F_0.8O_y (x = 0 or 0.02) were studied by x-ray diffraction analysis, scanning electron microscopy and by measuring resistances and current-voltage characteristics of the samples. The samples with x = 0.02 favour the growth of the 2223 phase with increased J_c values and decreased normal state resistivity ρ. In order to obtain maximum J_c values, the samples were synthesized at 836 °C prior to short-time partial melting at 849 °C.