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Oxygen Content and Valence of Ru in RuSr2(Gd0.75Ce0.25)2Cu2O10−δ (Ru-1222) Magnetosuperconductor

Oxygen Content and Valence of Ru in RuSr2(Gd0.75Ce0.25)2Cu2O10−δ (Ru-1222) Magnetosuperconductor The valence of Ru was analyzed for two RuSr2(Gd0.75Ce0.25)2Cu2O10−δ samples with different oxygen contents by Ru L III-edge x-ray absorption near-edge structure (XANES) spectroscopy. For the sample as-synthesized in 1 atm O2 the DC magnetization data measured in an applied field of 5 Oe showed a clear branching of the zero-field-cooled (ZFC) and field-cooled (FC) curves around 140 K, an up-turn for both around 100 K and a cusp at 85 K and a diamagnetic transition around 20 K in the ZFC part. A further confirmation for the superconductivity at 28 K was obtained from a resistance vs. temperature measurement. Annealing the as-synthesized sample in 100-atm O2 atmosphere at 420°C increased the diamagnetic transition temperature from 20 K to 40 K. According to a thermogravimetric analysis, the oxygen content increased accordingly by ca. 0.1 oxygen atoms per formula unit. Quantitative analysis of the XANES spectra using Sr2RuO4 (RuIV) and Sr2GdRuO6 (RuV) as reference materials revealed a valence value of +4.74 and +4.81 for Ru in the as-synthesized and the 100-atm O2-annealed sample, respectively. The obtained result suggests that the valence of Ru in Ru-1222 is affected by the change in oxygen content. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Low Temperature Physics Springer Journals

Oxygen Content and Valence of Ru in RuSr2(Gd0.75Ce0.25)2Cu2O10−δ (Ru-1222) Magnetosuperconductor

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References (9)

Publisher
Springer Journals
Copyright
Copyright © 2003 by Plenum Publishing Corporation
Subject
Physics; Condensed Matter Physics; Characterization and Evaluation of Materials; Magnetism, Magnetic Materials
ISSN
0022-2291
eISSN
1573-7357
DOI
10.1023/A:1023490202435
Publisher site
See Article on Publisher Site

Abstract

The valence of Ru was analyzed for two RuSr2(Gd0.75Ce0.25)2Cu2O10−δ samples with different oxygen contents by Ru L III-edge x-ray absorption near-edge structure (XANES) spectroscopy. For the sample as-synthesized in 1 atm O2 the DC magnetization data measured in an applied field of 5 Oe showed a clear branching of the zero-field-cooled (ZFC) and field-cooled (FC) curves around 140 K, an up-turn for both around 100 K and a cusp at 85 K and a diamagnetic transition around 20 K in the ZFC part. A further confirmation for the superconductivity at 28 K was obtained from a resistance vs. temperature measurement. Annealing the as-synthesized sample in 100-atm O2 atmosphere at 420°C increased the diamagnetic transition temperature from 20 K to 40 K. According to a thermogravimetric analysis, the oxygen content increased accordingly by ca. 0.1 oxygen atoms per formula unit. Quantitative analysis of the XANES spectra using Sr2RuO4 (RuIV) and Sr2GdRuO6 (RuV) as reference materials revealed a valence value of +4.74 and +4.81 for Ru in the as-synthesized and the 100-atm O2-annealed sample, respectively. The obtained result suggests that the valence of Ru in Ru-1222 is affected by the change in oxygen content.

Journal

Journal of Low Temperature Physics – Springer Journals

Published: Oct 7, 2004

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