Effect of Yb-substitution on thermally activated flux creep in the Bi 2 Sr 2 Ca 1 Cu 2-x Yb x O y superconductors

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GÜNDOĞMUŞ H., ÖZÇELİK B., Sotelo A., Madre M.

Journal of Materials Science: Materials in Electronics, cilt.24, sa.7, ss.2568-2575, 2013 (SCI-Expanded, Scopus)

Özet

In the present work, Bi 2 Sr 2 Ca 1 Cu 2-x Yb x O y (x = 0.0, 0.05, 0.1, and 0.25) superconductors were prepared by a polymer matrix route technique, and subsequently used as feed in a laser induced directional solidification (LFZ) process. The X-ray diffraction, DC magnetization and magnetoresistance measurements were studied. All samples consist mainly of the Bi-2212 phase which indicates the performed process is adequate. However, some impurity phases like CaCuO 2 were also detected. We have calculated the hole number using the relation given by Presland, and particle size, L hkl , using the XRD patterns results. From M-T results, the superconducting transition temperatures, T C , of the samples were found 93, 90, 87, and 85 K, respectively. The activation energies, irreversibility fields (H irr ), upper critical fields (H c2 ) and coherence lengths at 0 K (ζ(0)) were calculated from the resistivity versus temperature (R-T) curves, under DC magnetic fields up to 5 T. The thermally activated flux creep model has been studied in order to calculate the flux pinning energies. The results indicated that Hc2(0) varied from 132 to 30 T and the flux pinning energies varied from 650 to 400 meV at 0 T, with the content of Yb. © 2013 Springer Science+Business Media New York.