Tuning of dielectric properties of (ZnO)x-(CuTl-1223) nanoparticles-superconductor composites

Zinc oxide (ZnO) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10−δ (CuTl-1223) superconducting phase were prepared separately by sol–gel and solid-state reaction, respectively. ZnO nanoparticles were mixed with CuTl-1223 to get (ZnO)x-(CuTl-1223); x=0, 0.5, 1.0 and 1.5 wt% nanoparticles-superconductor composites, which were characterized by different experimental techniques. There was no change observed in crystal structure of host CuTl-1223 phase after addition of ZnO nanoparticles, which provide a clue about the occupancy of these nanoparticles at the grains-boundaries. The inclusion of ZnO nanoparticles was found to reduce the voids and to improve the inter-grains connectivity in the host CuTl-1223 phase. The zero resistance critical temperature {Tc(R=0)(K)} was increased by increasing wt% addition of ZnO nanoparticles in CuTl-1223 matrix. The dielectric properties of these samples i.e. dielectric constants (ε′rε′′r), and dielectric loss (tan δ), were determined by experimentally measuring the capacitance (C) and conductance (G) as a function of frequency at different operating temperatures. The values of dielectric parameters were decreased with the increase of frequency and become constant at certain higher frequency values, while the values of these parameters were increased with the increase of operating temperature values. So, we can tune the dielectric properties of CuTl-1223 superconducting phase by varying the content of ZnO nanoparticles, frequency and operating temperature.