Magnetoresistance Study of Y3Ba5Cu8O18 Superconducting Phase Substituted by Nd3+ and Ca2+ Ions


Superconducting samples of type Y3-𝑥Nd𝑥Ba5-𝑥Ca𝑥Cu8O18 with 0.0≤𝑥≤0.4 have been prepared via the solid-state reaction technique. The prepared samples were characterized using X-ray powder Diffraction (XRD) technique for phase analysis. The elemental content of the prepared samples was determined using Particle Induced X-ray Emission (PIXE). In addition, the oxygen content of these samples was obtained using non Rutherford Backscattering Spectroscopy (RBS) at 3 MeV proton beam. The results indicate that these substitutions do not affect the orthorhombic structure, while they decrease the oxygen-content of Y-358 phase. The electrical resistivity of the prepared samples was measured by the conventional four-probe technique from room temperature down to the zero superconducting transition temperature (T0). A slight change in the superconducting transition temperature (Tc) is observed for 0≤𝑥≤0.1, and then it decreases linearly with further increase in x. The linear decrease in Tc is attributed mainly to the partial substitution of Ba2+ ions by Ca2+ ions rather than the partial substitution of Y3+ ions by Nd3+ ions. The effect of magnetic f ields up to 4.44 kG on the electrical resistivity has been studied to investigate the vortex dynamics for the prepared samples. The experimental data, in the second stage of superconducting transition, fit well with the thermally activated f lux creep model and the activation energy U(B) shows a power law dependence on magnetic f ield as B-β. Also, the transition width is related to the magnetic f ields according to the relation Δ􀭘 􀰈 Bn. The values of β and n are strongly dependent on the Nd3+ and Ca2+ ions substitution. The magnetic f ield and temperature dependence of the activation energy U (B, T) is found to be U (B, T) ∽ Δ􀭘 􀰈 B-η, where η = β + n. Furthermore, the critical current density at zero temperature, Jc(0), as a function of the applied field was calculated for all the prepared samples. The result shows an enhancement in Jc(0) of Y-358 phase at x equals to 0.4 at different applied fields.


Awad R.K.


Rekaby M., RoumiƩ M., Abou-Aly A.I., Yousry M.

Journal/Conference Information

Journal of Superconductivity and Novel Magnetism,