Effects of Y and rare earth ions substitution for Ca in (Bi,Pb): 2223 superconductor

The effects of partial substitution of Ca by R = Y3+, Eu3+ and Er3+ on the structural and electrical properties in the ceramic superconductor (Bi1.6Pb 0.4)(ST1.8-Ba-0.2)(Ca1-xRx)(2) Cu3Oy (x = 0, 0.02) has been investigated. S ubstitutions by Y, Lu and Er in Ca site induced the decrease of volume frac tion for the "2223" phase and the increase of "2212" and "2201" volume phas es fractions. Above the excess conductivity region, all samples are charact erized by a linear temperature dependence of electrical resistivity. The ra te of depression for critical transition temperature in x = 0.02 samples is found to be almost the same for all substituents. The nature of T-c suppre sion may be attributed to the increase of oxygen content in Bi2O2 double la yers with increasing Y and rare earth concentration.