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Synthesis, Microstructure, Critical Current Density, Magnetization and Relaxation of Hot-Pressed YBa2Cu3O6+δ Through Partial Melting Post-Oxygenation

Published online by Cambridge University Press:  26 February 2011

P. J. Kunga ,
M. P. Maleya  and
M. E. Mchenry
P. J. Kunga
Affiliation:
ERDC, Los Alamos National Laboratory, P. O. Box 1663, MS K763, Los Alamos, NM 87545 Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University, Pittsburgh, PA 15213
M. P. Maleya
Affiliation:
ERDC, Los Alamos National Laboratory, P. O. Box 1663, MS K763, Los Alamos, NM 87545
M. E. Mchenry
Affiliation:
Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University, Pittsburgh, PA 15213
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Abstract

Hot-pressed YBa2Cu3O6+δ superconductor with plate-like grains annealed at the partial melting temperature ( ∼ 1,000 C) followed by slow cooling in oxygen atmosphere has resulted in enhanced magnetization hysteresis loops which show weak dependence on magnetic field. The X-ray diffraction pattern exhibits the significant features associated with the reflection (003) and (006), and a higher compaction density in hot-pressed samples compared with cold-pressed samples was observed from the SEM micrographs. Morphology study and microstructural analysis by SEM and TEM, respectively, indicate that grains were well aligned during hot-pressing mostly with their c-axes parallel to the pressing axis, and many intersecting twins were actually formed during post-oxygenation. Local oxygen-deficient regions likely existing in these hot-pressed and oxygenated samples are believed to act as effective flux pinning centers at high temperatures (∼ 50 K and above). The measurement of magnetic relaxation was employed to interpret the observed pinning behavior. The critical magnetization current density (Jc) calculated using the Bean model and the average grain dimension is in the order of 104 Amp/cm2 at 75 K up to 1 T. Because of a shorter period of oxygenation and a weak field dependence of Jc values, the process of hot-pressing combined with partial melting post-oxygenation is technologically practical in forming various shapes as desired from oxide superconductors.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 275: Symposium S – Layered Superconductors: Fabrication, Properties and Applications , 1992 , 287
Copyright
Copyright © Materials Research Society 1992

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References

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