Abstract

Nanocomposite materials of the Y3Ba5Cu8O18/(Ni0.5Zn0.5Fe2O4)x type, where x = 0.00 wt. %, 0.03 wt. %, 0.10 wt. %, and 0.50 wt. %, are synthesized by the improvement of the solid-state reaction technique. The prepared samples have been characterized by x-ray diffraction (XRD), scanning electron microscopy, x-ray energy dispersion, infra-red spectroscopy, thermo-gravimetric analysis, four probe DC resistance, and current–voltage (I–V) measurements. It was found that the prepared samples have an orthorhombic structure with unit cell parameters (a = 3.9557 Å, b = 3.8197 Å, and c = 30.2460 Å) for pure Y358, and the unit cell volume decreases by the addition of (Ni0.5Zn0.5Fe2O4) nanoparticles into the Y358 compound. The crystallite size (D) was evaluated from XRD patterns by Scherrer’s method. The crystallite size (D) is decreased from 40 nm for pure Y358 to 18 nm for Y358 doped by the Ni–Zn nanoferrite content of 0.50 wt. %. The critical current density Jc and I–V characteristics for superconductor/nanoferrite (Y358/Ni–Zn) composite materials are explained according to Bean’s critical state model and the charge–vortex duality in the Y358 high-Tc mixed-state.

Highlights

  • The first parent of the yttrium–barium–copper–oxide (YBCO) superconductor family was Y1Ba2Cu3O7−δ (Y123) with transition temperature Tc around 90 K.1 The discovery of Y123 opened the door to the high-Tc era of superconductivity above liquid nitrogen temperature

  • There are two groups studying the structure of Y358: the first group has reported that the lattice parameters of Y358 are almost similar to those of Y123,4 while the second group has reported unique lattice parameters of Y358 with triple-c values compared to the Y123 orthorhombic structure

  • The doping of Ni–Zn nanoferrites into Y358 decreases the percentage orthorhombicity, Δ = 100(a − b)/(a + b)

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Summary

Introduction

The first parent of the yttrium–barium–copper–oxide (YBCO) superconductor family was Y1Ba2Cu3O7−δ (Y123) with transition temperature Tc around 90 K.1 The discovery of Y123 opened the door to the high-Tc era of superconductivity above liquid nitrogen temperature. The first parent of the yttrium–barium–copper–oxide (YBCO) superconductor family was Y1Ba2Cu3O7−δ (Y123) with transition temperature Tc around 90 K.1. The discovery of Y123 opened the door to the high-Tc era of superconductivity above liquid nitrogen temperature. Bi–Sr–Ca–Cu–O (BSCCO), Tl–Ba–Ca–Cu–O, and Hg–Ba–Ca–Cu–O superconductors have higher Tc as 110 K, 123 K, and 135 K, respectively, but YBCO is less anisotropic than BSCCO, Tl–BCCO, and Hg–BCCO due to the presence of Cu–O chains between the CuO2 planes and is the preferred material for applications in higher magnetic fields.. An intensive research has been performed to enhance the transition temperature Tc and the electric current density Jc, which led to the fabrication of the new members of the YBCO family as Y3Ba5Cu8O18 (Y358) with Tc around 100 K.2. Bi–Sr–Ca–Cu–O (BSCCO), Tl–Ba–Ca–Cu–O, and Hg–Ba–Ca–Cu–O superconductors have higher Tc as 110 K, 123 K, and 135 K, respectively, but YBCO is less anisotropic than BSCCO, Tl–BCCO, and Hg–BCCO due to the presence of Cu–O chains between the CuO2 planes and is the preferred material for applications in higher magnetic fields. An intensive research has been performed to enhance the transition temperature Tc and the electric current density Jc, which led to the fabrication of the new members of the YBCO family as Y3Ba5Cu8O18 (Y358) with Tc around 100 K.2 Y358 has three CuO chains and five CuO2 planes, whereas Y123 has one CuO chain and two CuO2 planes. There are two groups studying the structure of Y358: the first group has reported that the lattice parameters of Y358 are almost similar to those of Y123,4 while the second group has reported unique lattice parameters of Y358 with triple-c values compared to the Y123 orthorhombic structure.

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