Dimensionality and superconducting parameters of YBa2Cu3O7−d/(WO3 NPs)x composites deduced from excess conductivity analysis

Abstract Superconducting composite products of type YBa2Cu3O7−d (noted Y-123) added with different contents (x wt.%) of tungsten oxide nanoparticles (WO3 NPs), x = 0.0 - 1.0 wt.%, were produced via the standard solid-state reaction technique. Samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrical resistivity measurements. XRD examination showed that the Y-123 orthorhombic structure is not altered by WO3 NPs additions. SEM observations indicated a reduction in the grains size with the increase of nanoparticles content. The investigation of the excess conductivity of different prepared composites was analyzed using Aslamazov-Larkin (AL) model. The investigated samples comprised of five distinct fluctuation regimes, namely short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuations regimes. The coherence length along c-axis at zero-temperature ( ), lower and upper critical magnetic fields ( and ), critical current density ( ) and numerous other superconducting parameters were estimated with respect to WO3 NPs content. Compared to undoped Y-123 sample, it was found that an amount of x = 0.05 wt.% of WO3 NPs is appropriate to improve the physical performances of Y-123, whereas with further increasing x, these performances were weakened.