Synthesis and Paraconductivity Studies of Fe–Pd Nanoparticles Added Cu0.5Tl0.5Ba2Ca3Cu4 O 12−δ Superconductors

Abstract

Cu0.5Tl0.5Ba2Ca3Cu4O12−δ/(Fe–Pd 0, 0.5, 1.0, 1.5 %) superconductors are prepared at normal pressure by using three-step method. Alloy of Cu0.5Tl0.5Ba2Ca3 Cu4O12−δ/(Fe–Pd 1 %) have shown maximum increase in the magnitude of superconductivity. Cu 0.5Tl 0.5 Ba2Ca 3Cu 4O12−δ/(Fe–Pd 0, 0.5, 1.0, 1.5 %) samples have shown Tc(R= 0) around 106, 105.3, 102, and 100 K and the onset of diamagnetism around 113, 110, 102, and 105 K, respectively. A comparison of X-ray diffraction (XRD) scans of Fe–Pd nanoparticles with Cu0.5Tl0.5Ba2Ca3Cu4O12−δ/(Fe–Pd 0.5, 1.0, 1.5 %) superconducting samples have shown that the nanoparticles of Fe–Pd are quite stable in the matrix of Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples even after repeated firing at 890 ∘C. With increase addition of Fe–Pd nanoparticles, the axes length increases, showing some inclusion of nanoparticle into the unit cell of Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples from the termination ends of crystal.The inclusion of Fe–Pd in the superconducting Cu0.5Tl0.5Ba2Ca3Cu4O12−δ grains is also evidenced in Fourier transform infrared spectroscopy (FTIR) absorption measurements. The Fe–Pd nanoparticles added in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples have been found to decrease the population of inter-grain voids that is found to increase the coherence length along the c-axis and the inter-layer coupling J. The FIC analysis of conductivity data haveshown the Fe–Pd nanoparticles diffusing into the inter-grain sites promoted an increase of penetration depth λp.d and Ginzburg–Landau parameter, κ. Due to the this possible diffusion of the Fe–Pd nanoparticles in the superconducting grains, the Tc(R= 0), Bc0(T), Bc1(T), and Jc(0) values are suppressed in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples.