Superconductivity Research Laboratory, Department of Physics, Barkatullah University, Bhopal-462 026, India
Abstract:
We have investigated the effect of Hg addition on the superconducting properties of BiSrCaCuO system. Polycrystalline samples with nominal composition Bi2Sr2−xHgxCa1Cu2Oy and Bi2Sr2−xHgxCa2Cu3Oy (x=0.3) were synthesized and used to investigate the phase evolution by XRD, superconducting behaviour by R–T measurement and the structural grain boundary effects by SEM. From these measurements, it has been noticed that the phases obtained with both types of compositions are the same as Bi2212 but the Tc values are different. With additional annealing, Tc zero values were raised from 60 to 72 K in Bi2Sr2−xHgxCa1Cu2Oy and 64 to 92 K in Bi2Sr2−xHgxCa2Cu3Oy. Also, an improved grain boundary linkage has been observed by SEM for the 92 K sample.