Effects of Rare Earth (RE=Ho, Sm) doping on the superconducting properties of YBCO

Abstract

The effects of Rare Earth (RE=Ho, Sm) doping on the superconducting properties of YBCO have been studied. Rare earths (Ho, Sm) have been doped in YBCO to partially substitute at Y site. Polycrystalline YBCO, Sm0.2Y0.8Ba2Cu3O7- (SYBCO) and Ho0.2Y0.8Ba2Cu3O7- (HYBCO) were prepared via the solid-state reaction route. Crystal structures were analysed by X-Ray Diffraction (XRD) which revealed that all samples have orthorhombic crystal structure. The lattice parameters and crystallite sizes have been calculated. The Resistance versus Temperature measurements performed by the four-probe method reveal the broadening of the superconducting transition in the doped samples as compared to that in YBCO. The Field Emission Scanning Electron Microscopy (FESEM) images have been used to observe the surface morphology of all the samples. The doped samples were also annealed to find out its effect on the properties of the doped samples. The results show that the crystal structure has been distorted and superconductivity is lost in both HYBCO and SYBCO.