Structural, Electrical and Magnetic Properties of FeO added GdBaCuO Superconductors

Abstract

In this study, the effects of FeO addition (0, 1, 2, 3, 4, 5, 10 and 20 wt %) on the structural, electrical and magnetic properties of GdBaCuO-123 (Gd-123) superconductor prepared by the conventional solid state method were investigated. The phase analysis and the lattice parameters of the materials were analyzed by X-ray diffraction (XRD) method. The critical temperatures (T_c) of the samples were determined from the resistance measurements by the standard four-point probe method. From these measurements, superconducting behaviour was observed for the addition of FeO up to 5 wt %. On the other hand, semiconducting behaviour was observed for higher FeO additions (10 and 20 wt %). The activation energies (U₀) were also evaluated by using the thermally-assisted-flux-flow (TAFF) model from the resistance measurements of the samples. It was observed that the activation energy of the samples decreased with the increase of the amount of FeO. The magnetic measurements of the samples (M-H) were carried out at 20 K with the Quantum Design PPMS system. Critical current densities (J_c) were calculated from the width of the M-H curves by using the Bean critical state model. According to the obtained results, the highest current carrying capacity belongs to 1 wt % added sample and has 1.2 × 10⁴ A/cm² value at 20 K and 0 T. It was also found that all samples were still carrying high currents even in high fields.