EFFECTS OF Y AND RARE EARTH IONS SUBSTITUTION for Ca in (Bi,Pb):2223 SUPERCONDUCTOR

Abstract

The effects of partial substitution of Ca by R = Y 3+, Eu 3+ and Er 3+ on the structural and electrical properties in the ceramic superconductor ( Bi 1.6 Pb 0.4) ( Sr 1.8- Ba 0.2) ( Ca 1-x R x)2, Cu 3 O y(x = 0, 0.02) has been investigated. Substitutions by Y, Lu and Er in Ca site induced the decrease of volume fraction for the "2223" phase and the increase of "2212" and "2201" volume phases fractions. Above the excess conductivity region, all samples are characterized by a linear temperature dependence of electrical resistivity. The rate 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 suppresion may be attributed to the increase of oxygen content in Bi 2 O 2 double layers with increasing Y and rare earth concentration.