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Abstract

Polycrystalline samples of YBa2Cu3O7-d have been synthesized via co-precipitation method with the inclusion of Gd2O3 (0 = x = 1.0). The effect of Gd2O3 nanoparticles on the superconducting properties and crystal structure of YBa2Cu3O7-d were investigated. The superconducting transition temperature (Tc) of each sample was measured by a standard four point probe method. As the inclusion of nano-Gd2O3 increases, the Tc of samples decrease from 92 K for x = 0.0 to 80 K for x = 1.0 wt% attributable to oxygen vacancy disorder. The crystal lattice parameters of all samples were determined by X-ray diffraction (XRD) with the Rietveld refinement technique. It was found that the samples are predominantly single phase perovskite structure Y-123 with orthorhombic and secondary phase, Y-211 for samples x = 0.2 - 1.0 wt%. The microstructural properties of samples were observed by Scanning Electron Microscope (SEM). The structure becomes more porous than the pure sample and the grain size significantly decrease. The addition of nano-Gd2O3 disturbs the grain growth of YBCO (123), thus resulting in the degradation of superconducting properties of the samples. The effect of Gd2O3 addition for intergranular critical current density, Jc and the presence of weak links that coupled the superconducting grains were also defined in AC susceptibility measurement in the range 0.005 Oe to 3.0 Oe.