Superconductivity dependent on the amount of Bi and Sr in the Bi2Sr2CuO6 compounds

Two series of samples with nominal compositions of Bi2+xSr2CuOy and Bi2Sr2−xCuOy (0⩽x⩽0.10) were prepared by a conventional solid-state reaction method. Laminar morphology is observed for all the samples under SEM. EDS analysis shows that Bi is slightly volatile, the depletion amount is about 3% in...

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Bibliographic Details
Published in:Physica. C, Superconductivity Superconductivity, 2007-09, Vol.460-462 (1), p.422-423
Main Authors: Wu, C.H., Chu, Y.C., Ling, D.C., Liu, S.H., Pong, W.F., Hseu, H.S., Chen, J.M., Lee, J.F., Kao, H.-C.I.
Format: Article
Language:English
Subjects:
Bi-L edge XANES
Bi2+xSr2CuOy
Bi2Sr2−xCuOy
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Effects of material synthesis, crystal structure, and chemical composition
Exact sciences and technology
Hole concentration
O-K edge XANES
Physics
Superconductivity
Transition temperature variations
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Summary:Two series of samples with nominal compositions of Bi2+xSr2CuOy and Bi2Sr2−xCuOy (0⩽x⩽0.10) were prepared by a conventional solid-state reaction method. Laminar morphology is observed for all the samples under SEM. EDS analysis shows that Bi is slightly volatile, the depletion amount is about 3% in the Bi rich samples, but only about 1% loses in the Sr deficient samples. Hole concentration of the Bi2Sr2−xCuOy series increases with increasing x, showing a hole doping effect caused by the depletion of the Sr ions. In contrary, Bi2+xSr2CuOy series has a hole filling effect by introducing the extra Bi ions. These samples show metallic conducting behavior in the normal state and superconducting property at lower temperature. Tc decreases with increasing x on both series. Bi2Sr2CuOy has the highest Tc at 7.9K with an optimal hole concentration of 0.237. Hole concentrations obtained from the O-K edge XANES spectra and the iodometric titration agree well in these samples.
ISSN:0921-4534
1873-2143
DOI:10.1016/j.physc.2007.03.107