Enhanced superconductivity in Cu0.5Tl0.5Ba2Can−1−yBeyCunO2n+4−δ (n=3n=3, 4 and y=0.7y=0.7, 1.5, 1.7, 2.0) system with oxygen doping

Enhanced superconducting properties in Cu0.5Tl0.5Ba2Can−1−yBeyCunO2n+4−δ   (n=3n=3, 4 and y=0.7y=0.7, 1.5, 1.7, 2.0) superconductors have been achieved by oxygen doping. The samples were prepared by solid-state reaction method and post-annealed in air, nitrogen and oxygen atmospheres for the study of oxygen exchange mechanism in the final component. It is observed from these studies that Beryllium substitution at Ca site improves the inter-plane coupling, which is further enhanced by the oxygen doping into the unit cell. The zero resistivity critical temperature [Tc(R=0)Tc(R=0)] is enhanced with post-annealing in oxygen atmosphere. The c  -axis length, observed by X-ray diffraction analysis has been found to decrease with increased Be contents in the unit cell. The softening of apical oxygen modes observed by FTIR absorption measurements also supports the enhanced inter-plane couplings. The higher electronegativity of Be compared with Ca is suggested to be a possible source of developing the improved inter-plane couplings. The enhanced superconducting properties in term of increased Tc(R=0)Tc(R=0) and quantity of diamagnetism are observed after post-annealing in oxygen.