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 TlBa 2 (Ca 2−y M y )Cu 3 O 9−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 TlBa 2 CaCu 2 O 9−δ and TlBa 2 Ca 3 Cu 4 O 9−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 CuO 2 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.