Crystal structures of highly-ordered long-period stacking-ordered phases with 18R, 14H and 10H-type stacking sequences in the Mg–Zn–Y system
| Autor: | Akira Yasuhara, Kyosuke Kishida, Haruyuki Inui, Kaito Nagai, Akihide Matsumoto |
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| Rok vydání: | 2015 |
| Předmět: |
Materials science
Polymers and Plastics Metals and Alloys Stacking Space group Crystal structure Electronic Optical and Magnetic Materials Crystallography Lattice constant Transmission electron microscopy Vacancy defect Scanning transmission electron microscopy Ceramics and Composites Hexagonal lattice |
| Zdroj: | Acta Materialia. 99:228-239 |
| ISSN: | 1359-6454 |
| DOI: | 10.1016/j.actamat.2015.08.004 |
| Popis: | The crystal structures of highly-ordered Mg–Zn–Y long-period stacking-ordered (LPSO) phases with the 18 R -, 14 H - and 10 H -type stacking sequences, which are constructed by stacking structural blocks composed of six, seven and five close-packed atomic layers, respectively, have been investigated by atomic-resolution scanning transmission electron microscopy (STEM) and transmission electron microscopy. The in-plane order characterized by the periodic arrangement of Zn 6 Y 8 atomic clusters on the lattice points of a 2 3 a Mg × 2 3 a Mg two-dimensional primitive hexagonal lattice ( a Mg : the lattice constant of Mg) is developed in the central four consecutive atomic layers in each of the structural blocks for the 18 R -, 14 H - and 10 H -type Mg–Zn–Y LPSO phases. The random occupation of the central site of each Zn 6 Y 8 atomic cluster with Mg, Zn, Y or vacancy is suggested through the analysis of the ultra-high resolution annular-bright field STEM images. The space groups of the most stable polytypes of the 18 R -, 14 H - and 10 H -type Mg–Zn–Y LPSO phases at 500 °C are determined to be C 2/ c , P 6 3 22 and Cmce , respectively. |
| Databáze: | OpenAIRE |
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