Significance of Cobalt Ferrite Nanoparticles on Superconducting Properties of Tl-1212 High Temperature Superconductor

Thallium-based high temperature superconductor (HTS) with nominal starting composition (Tl0.85Cr0.15)Sr2CaCu2O7-δ (Tl-1212) was prepared using high purity oxide powders via solid state reaction method. Small amounts (0.0 – 0.15 wt. %) of cobalt ferrite nanoparticles (CoFe2O4) were added into Tl-1212 superconductors. The effect of CoFe2O4 nanoparticles addition on the critical temperature (Tc), phase formation and microstructure properties including elemental compositional analysis were studied. The samples were investigated by the characterization of electrical resistance measurement, powder X-ray diffraction method (XRD), scanning electron microscopy and energy dispersive X-ray analysis (EDX). Zero-resistance temperature (Tc-zero) was found to reduce from 97 K to 89 K with increasing of CoFe2O4 nanoparticles concentration. Most of the samples indicated a dominant Tl-1212 phase of a tetragonal structure with a minor phase of Tl-1201. SEM micrographs with EDX mapping showed that CoFe2O4 nanoparticles were well distributed in all the samples.