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Phase Equilibria Studies Near the Superconducting YBa2Cu3Ox Composition by a Solid-State Ionic Technique

Published online by Cambridge University Press:  28 February 2011

Byung Tae Ahn ,
Turgut M. Gür ,
Robert A. Huggins ,
Robert Beyers  and
Edward M. Engler
Byung Tae Ahn
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305–2205
Turgut M. Gür
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305–2205
Robert A. Huggins
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305–2205
Robert Beyers
Affiliation:
IBM Almaden Research Center, 650 Harry Road San Jose, CA 95120–6099
Edward M. Engler
Affiliation:
IBM Almaden Research Center, 650 Harry Road San Jose, CA 95120–6099
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Abstract

This paper reports the findings of a phase-equilibrium study of the Y-Ba-Cu-O quaternary system in which the oxygen activity was monitored and controlled by a solid-state ionic technique. A stabilized zirconia electrolyte was used to titrate oxygen in or out of the sample and to monitor the oxygen activity inside a sealed sample chamber.

Compositions at or near YBa2Cu3Ox were studied at elevated temperatures in a wide range of oxygen pressures. All compositions indicated the presence of an invariant polyphase reaction- e.g., at 1 × 10-3 atm of oxygen pressure at 850 °C-- below which the superconducting phase becomes thermodynamically unstable and undergoes a decomposition reaction. Complementary x-ray diffraction analysis of samples prepared under well-defined oxygen pressures identified the phases present and, along with the oxygen coulometric titration data, allowed the construction of a portion of the relevant quarternary phase diagram.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 99: Symposium AA – High-Temperature Superconductors , 1987 , 171
Copyright
Copyright © Materials Research Society 1988

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References

REFERENCES

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