Effect of Mg and Be Doping on Superconducting Properties of TlBa2(Ca2−y M y )Cu3O9−δ (y=0 and 1.5 for M=Mg, Be) Superconductors

Abstract

In order to study the effect of an insulating charge reservoir layer, we have synthesized as-prepared and oxygen annealed TlBa2(Ca2−y M y )Cu3O9−δ (y=0 and 1.5 for M=Mg, Be) superconductors sample at atmospheric pressure using a solid-state reaction method. It has been found that the sample mainly contains tetragonal-1223 phase, but there exist some nominal derivative phases of TlBa2CaCu2O9−δ and TlBa2Ca3Cu4O9−δ superconductors. It is expected that doping of Mg and Be in place of Ca results in an increase in superconducting properties. But contrary to our expectation, both the [T c (R=0)] and magnitude of diamagnetism are decreased with the doping of Mg and Be in the final compound. This may be due to the scattering of the carriers in CuO2 planes resulting in the suppression of superconducting properties. The carrier concentration in these planes is optimized by carrying out a post-annealing experiment. Furthermore, FTIR absorption measurements are also incorporated.