Superconductivity in (Cu0.5Tl0.25Li0.25)Ba2Ca2Cu3-ySiyO10-δ samples

The (Cu0.5Tl0.25Li0.25)Ba2Ca2Cu3-ySiyO10-delta (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) superconductor samples have been prepared by solid-state reaction method. The critical temperature and as well as the magnitude of diamagnetism is increased up to Si concentration y = 1.0, however, from the doping level y = 1.25 a decrease in the critical temperature along with the vanishing of the diamagnetism was observed. The carrier's in the conducting CuO2/SiO2 planes were optimized by carrying out post-annealing in oxygen and an increase in the critical temperature was observed in all Si doped samples. The doping efficiency of Cu0.5Tl0.5Ba2O4-delta charge reservoir layer in (Cu0.5Tl0.25Li0.25)Ba2Ca2Cu3-ySiyO10-delta (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) samples is enhanced by doping Li+1 ion: as alkali metals are known to easily loose their outer most electron which could be supplied to CuO2/SiO2 conducting planes and would suppress the anti-ferromagnetism in the inner conducting planes. The FTIR absorption measurements have provided an indirect evidence of Si substitution at in CuO2 planes. (C) 2010 Elsevier Masson SAS. All rights reserved.