Improvement of structural and superconducting properties of Bi-2212 textured rods by substituting sodium

Abstract

In this paper, the physical and superconducting properties of Bi2Sr2Ca1−xNaxCu2O8+δ with x=0.0, 0.05, 0.075, 0.1, and 0.20 textured superconducting fiber rods prepared by a laser floating zone (LFZ) technique were studied. The effects of Na+1 substitution for Ca2+ have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transport measurements, dc-magnetization, magnetic hysteresis and magnetic critical current density. The powder XRD patterns of samples have indicated that Bi-2212 phase is the major one, independently of Na content. The best critical temperature, TC, has been found as 93.3K from M–T data for the sample with 0.075Na substitution. The maximum magnetic JC value has been calculated as 1.35×105A/cm2 at 10K for the 0.10Na sample. The maximum transport critical current density has directly been measured as 1.3×103A/cm2 at 77K for the 0.05Na sample.