Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1591541 | Solid State Communications | 2015 | 4 Pages |
Abstract
The thermal expansion of a AuâAlâYb intermediate-valence quasicrystal has been studied. X-ray diffraction measurements showed zero thermal expansion below 50Â K. By comparison with an isostructural AuâAlâTm quasicrystal, the contribution of the Yb valence variation was extracted, and it was shown that its negative thermal expansion component compensated for the positive thermal expansion of the original lattice. On cooling, the Yb contribution grew steeply below approximately 155Â K down to the lowest experimental temperature of 5Â K, due to enlargement of the Yb atomic radius, which was caused by the valence shift toward the divalent state. Additionally, a larger Yb contribution to the thermal expansion was demonstrated in a crystalline approximant to this quasicrystal. The magnitude of this contribution was approximately 1.4 times larger than in the case of the quasicrystal itself, resulting in a slight negative thermal expansion below 50Â K. A heterogeneous valence model for the quasicrystal that we proposed previously accounts for this magnitude difference.
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
T. Watanuki, S. Kashimoto, T. Ishimasa, A. Machida, S. Yamamoto, Y. Tanaka, M. Mizumaki, N. Kawamura, S. Watanabe,