Superconductivity of A15-and σ-phase of Nb-Ir |
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Authors: | H R Khan Ch J Raub K Lüders Z Szücs |
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Institution: | 1. Forschungsinstitut für Edelmetalle und Metallchemie, D-7070, Schw?bisch Gmünd, Germany 2. Institut für Atom-und Festk?rperphysik, Freie Universit?t Berlin, D-1000, Berlin 33, Germany
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Abstract: | The superconducting properties of A15-, σ-, and tetragonal phases of the system Nb−Ir were investigated. The alloys were prepared
by sintering and arc melting. They were subjected to optical and scanning electron microscopy. The lattice parameters were
determined by x-ray diffraction technique. Superconducting transition temperatures,T
c
, as well as upper critical fields,H
c2, were measured inductively and resistively. TheT
c
-values of the σ-phase vary between 2.15 and 2.40 K whereas for the A15-phase they vary between 1.83 and 2.73 K. TheT
c
-value of the tetragonal phase is 3.81 K. The upper critical fields of the tetragonal and the A 15-phase are nearly the same
(≈13 kG) and lower compared with that of the σ-phase (≈18 kG). Several theoretically predicted values ofH
c2(0) are evaluated and compared with the experimental ones. |
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Keywords: | 74 |
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