Electrical Resistivity and Magnetoresistance Studies of (Bi,Pb)-2223 Phase Substituted by Ru

Abstract

Series of Bi1.8Pb0.4Sr2Ca2.1Cu3−x Ru x O10+δ , (Bi,Pb)-2223, superconducting samples (with x=0.0, 0.025, 0.05, 0.075, 0.1125, 0.15, 0.3, and 0.4) were prepared by a solid-state reaction technique. The structural and the superconducting properties of our prepared samples were investigated using X-ray powder diffraction (XRD), scanning electron microscope (SEM), electron dispersive X-ray (EDX), electrical resistivity, and magnetoresistance measurements. The XRD showed the enhancement of (Bi,Pb)-2223 phase formation untiluntil x=0.05, beyond which a strong phase transition from (Bi,Pb)-2223 phase to (Bi,Pb)-2212 phase was observed. In addition, the superconducting transition temperature and the hole-carrier concentrations, determined from electrical resistivity measurements, increased as the Ru-contents increased untiluntil x=0.05. A systemic study of the magnetoresistance measurements for our prepared samples was carried out under applied weak magnetic fields started from 0.0 up to 4.4 kG, and their results were explained according to thermally activated flux creep and Ambegaokar and Halperin models. The calculated critical current density and upper critical magnetic field increased untiluntil x=0.05, and then decreased with further increased of Ru-contents. This indicated that the low-contents of Ru, 0.0<x≤0.05, can generate locally weak superconducting region that enhance flux pinning strength and hence improve the physical properties of (Bi,Pb)-2223 superconducting phase.