Transport properties on Bi-2212 superconductors can be improved by grain orientation methods while mechanical ones can be tuned up by the addition of metallic silver. Both processes can be performed simultaneously using the Laser Floating Zone (LFZ) method. In this work, Bi 2 Sr 2 CaCu 2 O x /3 wt.%Ag textured composite materials were prepared by a LFZ melting technique at different growth speeds (5, 15, 30, and 60 mm/h). In all cases, the observed microstructure after annealing shows the Bi-2212 phase as the major one.Although growth speed has no effect on the measured T c values, a drastic change on the J c values has been found. The best results, both mechanical and transport properties, have been obtained for samples grown at 15 mm/h.
In this study, the effect of Na substitution on the structural, electrical and magnetic properties of Bi 2 Sr 2 Ca 1-x Na x Cu 2 O 8+y superconductor with x=0.0, 0.05, 0.075, 0.1, 0.15, and 0.2 has been investigated. The effects of partial replacement of Na for Ca have been investigated by electrical resistivity (ρ-T), scanning electron microscopy (SEM), X-ray diffraction (XRD), and magnetic characterizations. XRD results have shown that the Bi-(2212) phase is the major one independently of the Na-concentration. SEM results indicate that the microstructure of samples is improved with increasing of Na-contents. From the electrical resistivity measurements it has been found that Tc is slightly higher than 92 K for Na-concentrations up to 0.20. Moreover, this trend is maintained in the magnetic measurements where the hysteresis loops are increased with increasing Na-concentrations. The maximum calculated Jc, using Bean's model, is around 10*10 6 A/cm 2 at 10 K and ∼ 1000 Oe for the 0.075 Na doped samples.
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