Abstract
The atomic structure of the Al 54Pd 31Sc 15 1/1-crystal approximant to the icosahedral quasicrystal has been studied using high-angle annular dark-field (HAADF) imaging in a scanning transmission electron microscopy (STEM). HAADF imaging directly reveals that the 1/1-phase has a periodic arrangement of Tsai-type atomic clusters, which consist of three successive shells with icosahedral symmetry as well as a disordered tetrahedron at the cluster center. In the 1/1-phase, the chemical ordering of Al and Pd is observed in the glue sites between the clusters, similar to that of Al and Au in the recently discovered Al 35Au 51Yb 14 1/1-phase, indicating a common structural feature of ternary Tsai-type approximants. Moreover, the preferential introduction of structural disorder into the second dodecahedral shell is observed in the HAADF images, which causes symmetry breaking of the 1/1-phase. On the basis of a comparison with the experimental and simulated images, a preliminary model for the atomic structure of the 1/1-phase is presented.
| Original language | English |
|---|---|
| Pages (from-to) | 7-11 |
| Number of pages | 5 |
| Journal | Journal of Alloys and Compounds |
| Volume | 543 |
| DOIs | |
| Publication status | Published - 2012 Dec 5 |
| Externally published | Yes |
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Keywords
- Al-Pd-Sc alloy
- Annular dark-field imaging
- Crystal approximant
- Icosahedral quasicrystal
- Scanning transmission electron microscopy
ASJC Scopus subject areas
- Mechanical Engineering
- Mechanics of Materials
- Materials Chemistry
- Metals and Alloys
Cite this
HAADF-STEM study of chemical ordering in Al-Pd-Sc 1/1-crystal approximant. / So, Yeong Gi; Nagao, Masahiro; Nagai, Takuro; Kimoto, Koji.
In: Journal of Alloys and Compounds, Vol. 543, 05.12.2012, p. 7-11.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - HAADF-STEM study of chemical ordering in Al-Pd-Sc 1/1-crystal approximant
AU - So, Yeong Gi
AU - Nagao, Masahiro
AU - Nagai, Takuro
AU - Kimoto, Koji
PY - 2012/12/5
Y1 - 2012/12/5
N2 - The atomic structure of the Al 54Pd 31Sc 15 1/1-crystal approximant to the icosahedral quasicrystal has been studied using high-angle annular dark-field (HAADF) imaging in a scanning transmission electron microscopy (STEM). HAADF imaging directly reveals that the 1/1-phase has a periodic arrangement of Tsai-type atomic clusters, which consist of three successive shells with icosahedral symmetry as well as a disordered tetrahedron at the cluster center. In the 1/1-phase, the chemical ordering of Al and Pd is observed in the glue sites between the clusters, similar to that of Al and Au in the recently discovered Al 35Au 51Yb 14 1/1-phase, indicating a common structural feature of ternary Tsai-type approximants. Moreover, the preferential introduction of structural disorder into the second dodecahedral shell is observed in the HAADF images, which causes symmetry breaking of the 1/1-phase. On the basis of a comparison with the experimental and simulated images, a preliminary model for the atomic structure of the 1/1-phase is presented.
AB - The atomic structure of the Al 54Pd 31Sc 15 1/1-crystal approximant to the icosahedral quasicrystal has been studied using high-angle annular dark-field (HAADF) imaging in a scanning transmission electron microscopy (STEM). HAADF imaging directly reveals that the 1/1-phase has a periodic arrangement of Tsai-type atomic clusters, which consist of three successive shells with icosahedral symmetry as well as a disordered tetrahedron at the cluster center. In the 1/1-phase, the chemical ordering of Al and Pd is observed in the glue sites between the clusters, similar to that of Al and Au in the recently discovered Al 35Au 51Yb 14 1/1-phase, indicating a common structural feature of ternary Tsai-type approximants. Moreover, the preferential introduction of structural disorder into the second dodecahedral shell is observed in the HAADF images, which causes symmetry breaking of the 1/1-phase. On the basis of a comparison with the experimental and simulated images, a preliminary model for the atomic structure of the 1/1-phase is presented.
KW - Al-Pd-Sc alloy
KW - Annular dark-field imaging
KW - Crystal approximant
KW - Icosahedral quasicrystal
KW - Scanning transmission electron microscopy
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UR - http://www.scopus.com/inward/citedby.url?scp=84865826571&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2012.07.119
DO - 10.1016/j.jallcom.2012.07.119
M3 - Article
VL - 543
SP - 7
EP - 11
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
ER -