Layer-specific hole concentrations in Bi2Sr2(Y1-xCax)Cu208+[delta] as probed by XANES spectroscopy and coulometric redox analysis

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© 2003 American Physical Society (APS). This is the accepted version of the following article: 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, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.67.134522.

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Journal Title

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Volume Title

School of Chemical Technology | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2003

Major/Subject

Mcode

Degree programme

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.

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Keywords

superconductors, hole concentrations, XANES spectroscopy, coulometric redox analysis

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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.