Dielectric properties of (Zn)_x/CuTl-1223 nanoparticle–superconductor composites

Zinc (Zn) nanoparticles and (Cu_0.5Tl_0.5)Ba₂Ca₂Cu₃O_10-δ (CuTl-1223) superconducting phase were prepared separately by sol–gel and solid-state reaction methods, respectively. Zn nanoparticles were added in CuTl-1223 superconducting matrix with different weight percentage during the final sintering process to obtain (Zn)_x/CuTl-1223 (x = 0–4 wt%) nanoparticle–superconductor composites. The effect of Zn nanoparticles on structural, morphological, superconducting, and dielectric properties of CuTl-1223 phase was investigated. The addition of these Zn nanoparticles has not affected the crystal structure of host CuTl-1223 superconducting phase. Superconducting properties were enhanced after the addition of Zn nanoparticles up to certain optimum content (i.e., x = 1 wt%), which were due to improved inter-grain connectivity by healing up of micro-cracks and reduction of defects like oxygen deficiencies, etc. The activation energy (U) was increased after the addition of Zn nanoparticles in CuTl-1223 phase. The dielectric properties of these samples (i.e., dielectric constant, dielectric loss) were determined by experimentally measured capacitance (C) and conductance (G) as a function of frequency at room temperature. The addition of metallic Zn nanoparticles in CuTl-1223 matrix has overall suppressed the dielectric parameters of (Zn)_x/CuTl-1223 nanoparticle– superconductor composites. The metallic Zn nanoparticles played a significant role in inter-grain couplings by filling the voids and pores.