Role of Co₃O₄ Nanoparticles in Dielectric Properties of Cu_0.5Tl_0.5Ba₂Ca₂Cu₃O_10-δ Superconducting Phase

Cobalt oxide (Co₃O₄) nanoparticles and Cu_0.5Tl_0.5Ba₂Ca₂Cu₃O_10-δ (CuTl-1223) superconducting phase were prepared by sol–gel and solid-state reaction methods, respectively. Co₃O₄ nanoparticles were added in CuTl-1223 superconducting matrix to get (Co₃O₄)_x/CuTl-1223, x = 0–2.0 wt.%, nanoparticles–superconductor composites. The unchanged crystal structure of the host CuTl-1223 superconducting phase (i.e. tetragonal) revealed that Co₃O₄ nanoparticles were settled at the grain boundaries. Superconducting properties of the CuTl-1223 phase were overall suppressed due to hole–charge carriers interaction at the grain boundaries. The dielectric properties of (Co₃O₄)_x/CuTl-1223 composites were investigated by varying the test frequencies from 40 Hz to 100 MHz and operating temperatures from 77 to 298 K. The values of dielectric properties were found maximal at lower frequencies and started to decrease at higher frequencies. So, the dielectric properties of the CuTl-1223 superconducting phase can be tuned by varying the contents of (Co₃O₄) nanoparticles, test frequencies as well as operating temperatures.