Excess conductivity investigations of WO3 nanowires added to YBa2Cu3O7-d superconductor

Abstract

Series of YBa2Cu3O7-d + x wt% WO3 nanowire mixtures where x = 0.0–2.0 wt% were prepared via solid-state reaction method. X-ray diffraction (XRD) patterns show the unaffected orthorhombic structure in various composites. Scanning electron microscopy (SEM) micrographs show the increase in grains size and the filling of voids between grains by WO3 nanowires. The superconducting transition temperatures deduced from electrical resistivity versus temperature (ρ(T)) measurements are almost unchanged by lower WO3 nanowires addition (i.e., x 0.5 wt%). The analysis of excess conductivity fluctuation (∆σ) by means of Aslamazov–Larkin (AL) and Lawrence–Doniach (LD) approaches was investigated. Dimensional fluctuations, coherence lengths, effective layer thickness, zero temperature lower and upper critical magnetic fields (Bc1 (0) and Bc2 (0)), and critical current density at temperature T = 0 K (Jc(0)) were extracted and discussed in relation with the structure and morphology. Improvements in Bc1 (0), Bc2 (0), and Jc(0)) were noticed for samples added with lower WO3 nanowires content, particularly for x = 0.1 wt% composite sample.