Layer-specific hole concentrations in Bi2Sr2(Y1-xCax)Cu208+[delta] as probed by XANES spectroscopy and coulometric redox analysis
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School of Chemical Technology |
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2003
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Language
en
Pages
134522/1-6
Series
Physical Review B, Volume 67, Issue 13
Abstract
Induction of holes not only in the superconductive CuO2 plane but also in the Bi2O2+δ charge reservoir of the Bi2Sr2(Y1-xCax)Cu2O8+δ superconductor upon CaII-for-YIII substitution is evidenced by means of two independent techniques, i.e., high-resolution x-ray-absorption near-edge structure (XANES) spectroscopy measurements and coulometric redox titrations. The absolute values derived for the CuO2-plane hole concentration from the Cu L2,3-edge XANES spectra are in good agreement with those obtained from the coulometric redox analysis. The CuO2-plane hole concentration is found to increase from 0.03 to 0.14 concomitantly with the increase in the BiO1+δ/2-layer hole concentration from 0.00 to 0.13 as the Ca-substitution level, x, increases from 0 to 1. The threshold CuO2-plane hole concentration for the appearance of superconductivity is determined at 0.06, while the highest Tc is obtained at the hole concentration of 0.12. In the O K-edge XANES spectrum, the increases in the CuO2-plane and BiO1+δ/2-layer hole concentrations with increasing x are seen as enhancement in the relative intensities of the pre-edge peaks at ∼528.3 and ∼530.5 eV, respectively.Description
Keywords
superconductors, hole concentrations, XANES spectroscopy, coulometric redox analysis
Citation
Karppinen, Maarit & Kotiranta, M. & Nakane, T. & Yamauchi, H. & Chang, S. C. & Liu, R. S. & Chen, J. M. 2003. Layer-specific hole concentrations in Bi2Sr2(Y1-xCax)Cu208+[delta] as probed by XANES spectroscopy and coulometric redox analysis. Physical Review B. Volume 67, Issue 13. 134522/1-6. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.67.134522.
