Effects of Gd2O3 addition in YBa2Cu3O7−δ on the critical current density

Abstract

Y Ba 2 Cu 3 O 7 − δ (YBCO) powders with Gd2O3 additives are prepared by the solid state reaction method. X-ray diffraction with Rietveld refinements shows that both Gd2O3 and YBCO phases coexist in the products. With increasing additive content, the unit cell symmetry of YBCO phase remains unchanged but the grain size increases. The critical current density (Jc) exhibits a maximum at x=0.1 in YBCO+ xGd2O3 systems. Moreover, the addition of Gd2O3 in YBCO enhances Jc by applying the magnetic field, although the superconducting temperature (Tc) decreases slightly. We argue that the characteristic behavior of Jc may come from the counterbalance of two effects simultaneously, which was caused by the variation of superconductivity and the inhomogeneity of grain distribution in nanoscale.