Hasan Ağıl - Department of Material Science and Engineering, Faculty of Engineering, Hakkari University, Hakkari, Turkey
Nurcan Akduran - Technology Department, Sarayköy Nuclear Research and Training Centre, Turkish Atomic Energy Authority, Ankara, Turkey

In this study, the effects of FeO addition (۰, ۱, ۲, ۳, ۴, ۵, ۱۰ and ۲۰ wt %) on the structural, electrical and magnetic properties of GdBaCuO-۱۲۳ (Gd-۱۲۳) 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 (Tc) 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 ۵ wt %. On the other hand, semiconducting behaviour was observed for higher FeO additions (۱۰ and ۲۰ wt %). The activation energies (U۰) 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 ۲۰ K with the Quantum Design PPMS system. Critical current densities (Jc) 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 ۱ wt % added sample and has ۱.۲ × ۱۰۴ A/cm۲ value at ۲۰ K and ۰ T. It was also found that all samples were still carrying high currents even in high fields.

GdBaCuO superconductor; FeO addition; Flux pinning; Critical current density