Sn doped (Cu0.5Tl0.5)Ba2Ca2Cu3−ySnyO10−δ superconductors: Effect on the diamagnetism and phonon modes

Abstract

Sn doped (Cu0.5Tl0.5)Ba2Ca2Cu3−ySnyO10−δ (y=0,0.25,0.5,0.75,1.0,1.25,1.50) superconductors have been synthesized by using solid state reaction method. The crystal structure of these Sn doped samples is orthorhombic and the axis lengths are found to increase with enhanced Sn doping concentration. The critical temperature and the magnitude of the diamagnetism are suppressed with enhanced doping of Sn. The samples turn into an insulator with very high room temperature resistivity if the Sn doping concentration is increased beyond y=1.5. The carrier’s concentration in the conducting CuO2/SnO2 planes has been enhanced by carrying out post-annealing experiments in the air and oxygen atmosphere. The increased concentration of holes in CuO2/SnO2 planes resulting out of oxygen diffusion in the material is evidenced by increased intensity of Oδ mode of oxygen measured by Fourier transform infrared absorption measurements and also by oxygen contents measured by iodometric titration method.