| Summary: | 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.
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