The effects of NiO nanoparticles addition in YBa2Cu3O7-δ (YBCO) superconductors had been investigated. YBCO superconductor powders were prepared by using high purity oxide powders via solid state reaction method. 0.01 0.05 wt.% of NiO nanoparticles were added into YBCO. The critical temperature (Tc) and transport critical current density (Jc) were determined by using four point probe method. The lattice parameters and morphology of the samples were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively. Tc of YBCO increased from 84 K to 87 K with 0.02 wt.% of NiO nanoparticles addition. The addition on NiO nanoparticles have significantly enhanced transport critical current density of YBCO by acting as flux pinning centers. YBCO with 0.03 wt.% of NiO nanoparticles performed the highest Jcup to 1265 mA/cm2 among the NiO-added samples. However, excessive addition of NiO nanoparticles in YBCO caused degradation in Tc and Jc.

<p>The effects of gamma ray irradiation on high temperature superconductors YBa2Cu3O7-δ with nano particles Fe3O4 (20-30 nm) addition were investigated. YBCO superconductor powders were prepared by using high purity oxide powders via solid state reaction method. 0.01 – 0.05 wt.% of nano particles were added into YBCO. Samples were irradiated with 100 kGy gamma ray. The critical temperature (Tc) and transport critical current density (Jc) were determined by using four point probe method. The lattice parameters and morphology of the samples were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively. The results before and after gamma ray irradiation were compared. All of the samples showed increased Tc-zero after 100 kGy gamma ray irradiation. However, the Jcwas degraded after gamma ray irradiation. There is no significant variation found in the XRD patterns. The porosity of the samples was increased by the gamma ray irradiation. It can be concluded that gamma ray irradiation has enhanced the superconducting properties but degraded the transport properties.</p>