Ho arrangement in the Zn6Mg3Ho icosahedral quasicrystal studied by atomic-resolution Z-contrast STEM.
The atomic structure of the Zn6Mg3Ho icosahedral quasicrystal has been studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) with Z-contrast (Z: atomic number). We demonstrate that in particular Z-contrast imaging is quite powerful for specifying heavy atom positions in the quasicrystalline compound, as shown by a comparison with high-resolution phase-contrast imaging. It is confirmed that the observed Z-contrast images are fairly well explained by the projected potential of only the Ho atomic arrangement, which was recently proposed by X-ray diffraction analysis; Ho occupies an even-body-center site of the 3-dimensional Penrose lattice. Consequently, the present direct structural observation strongly supports the validity of the proposed Ho site.
Abe
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National Institute for Materials Science, Tsukuba, Japan. abe.eiji@nims.go.jp
Takakura
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Tsai
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AP