Structural and physical properties of Cd-doped Bi1.64Pb0.36Sr2Ca2−xCdxCu3Oy superconductor

The effect of Cd doping on structure and physical properties of the Bi–Pb–Sr–Ca–Cu–O system with a nominal starting composition of Bi1.64Pb0.36Sr2Ca2−xCdxCu3Oy (BPSCCC; x=0.0, 0.02, 0.04, 0.1, 0.5, 1 and 2) was studied. The BPSCCC superconductor was made by a solid state reaction method. Structural analysis was carried out using XRD, SEM and EDX measurements. The critical temperature, critical current density and flux pinning energy were measured by the standard four-probe method. The resistivity of Cd-doped samples at room temperature increased in proportion to the increase in amounts of Cd. On the contrary, it decreased as the annealing time increased. Also for all samples the relation between current and voltage in the mixed state was found to follow the model relationship V=αIβ. In addition, a small amount of doping (x=0.04) has been found to improve the superconducting properties of the Bi–Pb–Sr–Ca–Cu–O system.