Effect of site selective doping of Sm on the superconducting and flux pinning properties of (Bi, Pb)-2212

The effect of site selective doping of Sm on the superconducting and flux pinning properties of (Bi, Pb)-2212 superconductor has been investigated. Pure, Sm substituted at different cationic sites such as Bi, Sr and Ca, and Sm added (Bi, Pb)-2212 superconducting samples are prepared by solid state synthesis. Remarkable improvements in the TC, JC and flux pinning properties have been observed both in the Sm substituted and Sm added samples and the properties are found to be highly site dependent. The bulk flux pinning force (FP) calculated from the field dependent JC values shows that the irreversibility lines of Sm doped samples are shifted towards higher fields to different extents depending on the site in which the substitution or addition is made. These changes are due to a decrease in hole concentration and the creation of point-like defects because of the replacement of cations by rare earth ions and also may be due to nanoscale secondary phases present in the samples.