Effect of Sm-substitution on the electrical and magnetic properties of (Tl0.8Hg0.2)-1223

Bulk Tl0.8Hg0.2Ba2Ca2-xSmxCu3O9-delta superconducting samples with x = 0.00, 0.025, 0.05, 0.10, 0.15, and 0.20 were prepared, in a sealed quartz tube, by a single step solid-state reaction technique. The prepared samples were investigated using X-ray powder diffraction, scanning electron microscope, electron dispersive X-ray, electrical resistivity, ac magnetic susceptibility and electron paramagnetic resonance. Powder X-ray diffraction analysis revealed that the prepared samples are nearly single phase of (Tl, Hg)-1223 with tetragonal structure (space group P/4mmm). The temperature dependence of the electrical resistivity and the ac magnetic susceptibility was investigated to study the effect of Sm-substitution, on the superconducting transition temperature T-c and the intergrain critical current density J(c). The data showed a T-c suppress as Sm-content increases, whereas J(c) increases up to x = 0.05, after that it depresses with further increase in x. Furthermore, electron paramagnetic resonance (EPR) spectrum at room temperature was studied for the prepared samples. The values of the gyromagnetic factors, g(perpendicular to), g(parallel to), the hyperfine structure and the spin density were calculated as a function of Sm-content. (C) 2009 Elsevier B.V. All rights reserved.