Superconductivity in (Cu 0.5Tl 0.25Li 0.25)Ba 2Ca 2Cu 3− ySi yO 10− δ samples

Abstract

The (Cu 0.5Tl 0.25Li 0.25)Ba 2Ca 2Cu 3− y Si y O 10− δ ( 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 CuO 2/SiO 2 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 Cu 0.5Tl 0.5Ba 2O 4− δ charge reservoir layer in (Cu 0.5Tl 0.25Li 0.25)Ba 2Ca 2Cu 3− y Si y O 10− δ ( 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 CuO 2/SiO 2 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 CuO 2 planes.