EFFECT OF HEATING RATE ON THE PROPERTIES OF BISMUTH-BASED SUPERCONDUCTING MATERIALS

Abstract

Bismuth based superconducting materials having a general formula Bi_2-x Pb_0.4Sr₂Ca₂ Cu₃O_y (where x = 0.1, 0.2, 0.3 and 0.4) were synthesized by the simple solid-state reaction method. Each of the samples was initially calcined at three temperatures of 790^oC at different heating rates of 2, 5, 10, 14 and 20 ^oC min^-1 for 24h. The sample pellets were sintered in air at three different temperatures of 835^oC for 48 h at the heating rates given above. The lattice parameters (a, b and c) and unit cell volume, V_cell, of the samples were calculated by X-ray diffraction (XRD). The dc electrical resistivity and ac magnetic susceptibility measurements show that the sample with the value of x = 0.3, sintered at 835^oC, at a heating rate of 14^oC.min^-1 has the highest percentage of the high-T_c (2223) phase, the highest value of T_c(0) =106 K and the lowest room temperature resistivity value.