Effect of Yb-substitution on thermally activated flux creep in the Bi2Sr2Ca1Cu2-xYbxOy superconductors

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

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, cilt.24, sa.7, ss.2568-2575, 2013 (SCI-Expanded) identifier identifier

Özet

In the present work, Bi2Sr2Ca1Cu2-xYbxOy (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 CaCuO2 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 (zeta(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.

In the present work, Bi2Sr2Ca1Cu2-xYbxOy (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 CaCuO2 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 (zeta(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