Role of Nd2O3 nanoparticles addition on microstructural and superconducting properties of YBa2Cu3O7–δ ceramics

Abstract

The effects of Nd2O3 nanoparticles addition on microstructure, transport and AC susceptibility properties of YBa2Cu3O7–δ (Y123) superconductors were systematically investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM), four point probe measurement and AC spectrometer. It was found that the added samples were predominant by Y-123 phase beside small amount of Y-211 and unreacted Nd2O3 secondary phases. All added samples preserved the orthorhombic structure similar to the pure sample and no orthorhombic-to-tetragonal transition occurred. The samples became more porous and their grain size significantly decreased with addition of Nd2O3. The addition of nano-Nd2O3 disturbed the grain growth of Y123, thus resulting in the degradation of superconducting properties of the samples. The superconducting transition temperature (Tc onset) of samples decreased from 92 K for x=0.0 to 78 K for x=1.0 wt.%, which could be attributable to oxygen vacancy disorder. From AC susceptibility result, the inter- and intra-granular loss peaks became wider and broader with increase of Nd2O3 addition due to the weakening of grains coupling. On the other hand, the inter-granular critical current density, Jcm, was found to increase with Nd2O3 addition and had the highest value at x=0.6, confirming that Nd2O3 nanoparticles acted as pinning centers in Y123 matrix.