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Superconducting Properties and Flux Pinning in Liquid Quenched Nb-Ga Alloys

Published online by Cambridge University Press:  15 February 2011

Gregory B. Clemente
Affiliation:
Gordon McKay Laboratory, Harvard University, Cambridge, MA 02138, USA
F. Habbal
Affiliation:
Gordon McKay Laboratory, Harvard University, Cambridge, MA 02138, USA
J. Bevk
Affiliation:
Gordon McKay Laboratory, Harvard University, Cambridge, MA 02138, USA
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Abstract

Nb75−xGa25+xtapes (1≤ x ≤ 6) were prepared by liquid quenching technique in an argon atmosphere. The transition temperature Tc, upper critical field Hc2 and critical current density Jc were measured in both as-quenched and annealed samples. The values of Tc (onset) ranged from 16.5 to 18.0K in the asquenched samples and increased upon annealing up to 20.0 K. Similar increase was also observed in the values of Hc2 (4.2 K) from ∼190 kOe to values higher than the attainable field of 220 kOe. For annealed samples near stoichiometric composition, Hc2 was estimated to be higher than 300 kOe. The critical current densities of these tapes are relatively low [Jc (4.2 K) ≤ 2 × 104A/cm2] compared to other melt-quenched A-15 compounds. Flux pinning force, FP, does not obey a single scaling law. The existence of two peaks in FP at low temperatures and of only one peak at 13.4 K for 1 ≤ x ≤ 4 is discussed in terms of the microstructural characteristics of the samples.

Type
Research Article
Copyright
Copyright © Materials Research Society 1982

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Footnotes

*

Present address: Bell Labs, Murray Hill, NJ 07974, USA

References

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