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Materials Aspects of Oxide Superconductors - Effect of Ambient Water on Superconductivity-

Published online by Cambridge University Press:  28 February 2011

K. Kitazawa
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
K. Kishio
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
T. Hasegawa
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
A. Ohtomo
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
S. Yaegashi
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
S. Kanbe
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
K. Park
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
K. Kuwahara
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
K. Fueki
Affiliation:
Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
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Abstract

It has been found that the chemical instability of Ba2LnCu3O7 causes some problems in the measurements of critical temperature and creates a highly resistive grain boundary contact which is the major cause of the low critical current density at the present moment. Firstly, measurements of the superconductive critical temperature could be seriously misled if based solely on resistive transition because apparent resistivity anomaly is observed due to electrochemical EMF which appears when the electrode contact is attacked by water. Secondly, the barrier nature of the grain boundary against charge carriers is significantly enhanced by the chemical attack of the boundary region with water and water/carbon dioxide in the annealing atmosphere. This leads to a further weakening of the Josephson weak link between polycrystalline grains in the high Tc oxide superconductors.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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References

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