Effects of MnFe_2O_4 nanoparticles on dielectric properties of Cu_(0.5)TI_(0.5)Ba_2Ca_2Cu3O_(10-δ) superconducting phase

摘要

Magnetic manganese ferrite (MnFe2O4) nanoparticles were synthesized by sol-gel method and solid-state reaction method was chosen for preparation of the superconducting Cu0.5Tl0.5Ba2Ca2Cu3O10-delta (CuTl-1223) phase. Superconducting-nanoparticles (MnFe2O4)(x)/CuTl-1223; x = 0-2.0 wt% composites were obtained by adding MnFe2O4 nanoparticles in CuTl-1223 superconducting matrix. The unchanged tetragonal crystal structure of the host CuTl-1223 superconducting phase witnessed that MnFe2O4 nanoparticles were not decomposed and settled at the grain-boundaries. The superconductivity was over all suppressed due to the reduction of superconducting volume fraction and enhanced scattering cross-section of the mobile charge carriers across these magnetic MnFe2O4 nanoparticles settled at the grain-boundaries of the host superconducting CuTl-1223 phase. The frequency dependent dielectric properties of (MnFe2O4)(x)/CuTl-1223 composites were probed at different operating temperatures. Different dielectric parameters (i.e. E >'(r,) E > aEuro(r)(3), tan delta and sigma (ac)) were determined from the experimentally measured capacitance (C) and conductance (G). The variation of these dielectric properties of CuTl-1223 superconducting phase with the variation of test frequency, contents of MnFe2O4 nanoparticles and operating temperature were investigated, correlated, compared and explained. These investigations can be very useful for the selection criteria of the materials for the practical applications.