Substitution of 3d metals for Cu in (Bi, Pb)2Sr2Ca2Cu3Oy

Abstract The effect of the substitution of Mn, Fe, and Zn for Cu on the superconducting properties of (Bi, Pb) 2 Sr 2 Ca 2 Cu 3− x M x O y (0≤ x ≤0.5) has been investigated by means of X-ray diffraction, DC magnetic susceptibility and electrical resistivity measurements. The temperature at which the resistivity is zero decreases monotonically with x in the region x ≤0.07 for the Zn- and Fe- doped samples. The Fe-doped samples with x >0.1 are not superconducting while the corresponding Zn-doped samples are superconducting with the amount of the 2212 phase increasing with increasing Zn concentration. The effect of Mn doping on the superconductivity is less than that of Zn and Fe. There is evidence of weak links between superconducting grains. Pair-breaking effects due to the effect of doping seem to give a satisfactory explanation of the reduction in T c . The results for the low dopant concentrations lead to the conclusion that local disorder rather than magnetism is the important factor for the suppression of superconductivity in the samples.