Effect of Na substitution on superconducting properties of Bi-2212 ceramics prepared by Sinter-Forged process

摘要

Bulk textured Bi2Sr2Ca1-xNaxCu2Oy (x = 0.0, 0.05, 0.0750.1,0.15, and 0.20) ceramics have been prepared by a polymer solution method followed by sinter-forging process. The microstructure and superconducting properties of textured samples were affected by Na substitution. According to XRD data, all samples show that Bi-2212 phase is the major one, and main peaks corresponded to the (00l) diffractions confirming that the crystallographic c-axis is perpendicular to the surface. SEM micrographs showed that samples are composed of well-stacked and oriented grains. The best critical temperature, T-c, was measured as 85.6 k for x = 0.075. The critical current densityJc, values decrease gradually with the increase of applied magnetic field. The maximum calculated Jc was 1.38 x 10(5)A/cm(2) at 10 K for 0.075 Na sample which is about four times higher than the 0.34 x 10(5) A/cm(2) value determined for the pure sample. The anisotropic properties of these textured materials have been investigated using magnetic measurements. (C) 2016 Elsevier Ltd. All rights reserved.