Synthesis and superconducting properties of (Au)x/CuTl-1223 composites

Abstract

We explored the feasibility of synthesizing (Au)x/(Cu0.5Tl0.5)Ba2Ca2Cu3O10−δ {(Au)x/CuTl-1223};x=0, 0.5, 1.0, and 1.5wt.%, nano-superconductor composites by two steps solid-state reaction. We investigated the effect of gold (Au) nanoparticles on the structural and superconducting properties of CuTl-1223 matrix. These composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) absorption spectroscopy, ac-susceptibility (χac) and dc-resistivity (ρ) measurements. We observed the tendency of Au nanoparticles to occupy the inter-granular spaces (grain-boundaries) as the tetragonal structure of CuTl-1223 superconducting matrix remained unaltered after the addition of Au nanoparticles. The improvement in the superconducting properties after the addition of Au nanoparticles can be attributed to an increase in the inter-grains connectivity by healing up the inter-grains voids and pores by these nanoparticles. The improved inter-grains connections can facilitate the carriers transport across the inter-crystallite sites. But the superconducting volume fraction starts to be decreased after certain optimum inclusion level of Au nanoparticles, which causes the suppression of superconductivity parameters. The non-superconducting metallic Au nanoparticles reduce the superconducting volume fraction beyond certain optimum level of Au nanoparticles inclusion in superconducting state of CuTl-1223 matrix.