Effect of Pr and Ca doping on the superconducting properties of Dy 1-2x,Prx,Cax,Ba2Cu3O 7-δ HTSCs

Abstract

The structure changes and the suppression of superconductivity in the Dy-123 high-temperature superconductors (HTSCs) due to equal substitution of Pr and Ca are studied. The onset temperatures (Tc's) of the co-doped Dy1-2PrxCaxBa2Cu3O 7-δ HTSC's are measured by AC susceptibility measurements. The Tc's and rates of decrease of dTc/dx due to Pr substitution for both series exhibit rare earth size effects. It is found that the lattice distortion defined by D = (b - a)/(b + a), where a and b are the lattice parameters in the basal plane, decreases systematically as the doping is increased. A hole-filling and pair-breaking model is used to explain the behaviors of both the Tc's and the rates of decrease of dT c/dx as Pr4+ ions are doped into two "123" HTSCs. © World Scientific Publishing Company.