Three-dimensional model of structural transformation from icosahedral to hexagonal structure (μAl4Mn)

Lann, A. Le; Shoemaker, C. B.

doi:10.1016/0022-3093(93)90434-y

Cited by 11 publications

(4 citation statements)

References 6 publications

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“…Straightforward application of direct methods did not produce a structural model that would refine to a R factor below 50%. The hexagonal µ-Al 4 Mn phase is an important approximant of the Al-Mn decagonal quasicrystal (Audier and Guyot 1986, Bendersky 1987, Shoemaker et al 1989, Le Lann and Shoemaker 1993, Sui et al 1997. The hexagonal µ-Al 4 Cr (Kuo 1990, Bendersky et al 1991, Wen et al 1991, 1992, Audier et al 1995 is isostructural to it.…”

Section: Structure Determinationmentioning

confidence: 99%

Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Deng¹,

Kuo

2004

J. Phys.: Condens. Matter

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The crystal structure of the orthorhombic phase Al4(Cr,Fe) with a composition of Al80.6Cr10.7Fe8.7 has been determined by single-crystal x-ray diffraction (table 2). There are 11 crystallographically independent Cr/Fe sites, of which 10 are icosahedrally coordinated. Of the 28 crystallographically independent Al sites 5 are icosahedrally coordinated. However, owing to the presence of many partial occupancies, caused by split atoms, some of these coordinations are only pseudo-icosahedral with effective coordination numbers (section 4.3). The icosahedral and pseudo-icosahedral clusters are oriented with a two-fold axis parallel to [100]. They are linked either by vertex-, edge- or face-sharing or by mutual interpenetration, thus forming large clusters of icosahedra in the (100) layers with one of the five-fold axes in the [010] direction. Four of the 12 atoms defining the vertices of an icosahedral cluster lie in a mirror plane (F plane), while the other atoms are in puckered layers below and above the mirror plane. Thus, the icosahedral cluster consists of layers of three atoms thick. Two such layers stack within one lattice constant nm. The interconnection of icosahedra in the layer block forms large triangular and hexagonal structural motifs, though they have only two-fold rotational symmetry. Similar geometrical motifs but displaying three- or six-fold symmetry do exist in the structure of the hexagonal μ-Al4Mn, κ-(AlCrNi), λ-Al4Mn and ν-Al12Cr2Fe phases.

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Section: Structure Determinationmentioning

confidence: 99%

Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Deng¹,

Kuo

2004

J. Phys.: Condens. Matter

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“…The -Al 4 Mn phase yields electron diffraction patterns similar to those of icosahedral and decagonal quasicrystals (Bendersky, 1987), and its structure has a large hexagonal unit cell (with the space group P6 3 /mmc, lattice constants a = 19.98 A ˚, c = 24.673 A ˚, and containing 563 atoms), as determined by Shoemaker et al (1989). They used this phase to deduce structural models for icosahedral quasicrystals in the Al-Mn system (Le Lann & Shoemaker, 1993). Kreiner & Franzen (1995) described the structure of the -Al 4 Mn phase on the basis of the cluster concept.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics investigation of a one-component model for the stacking motif in complex alloy structures

Yeh¹,

Tomita²,

Imanari³

et al. 2022

J Appl Cryst

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Developing realistic three-dimensional growth models for quasicrystals is a fundamental requirement. The present work employs classical molecular dynamics simulations to investigate the adsorption of Al on a close-packed Al layer containing atomic vacancies. Simulation results show that the adsorbed Al atoms are located preferentially above and below the atomic vacancies in the close-packed layer, and the results obtained from a one-component system of atoms interacting via an interatomic pair potential for Al–Al appropriately reproduce the stacking motif seen in complex alloys such as the μ-Al4Mn phase. The simulations also reveal the formation of a deformed icosahedron. These results provide new insights into the growth mechanism and origin of complex alloys and quasicrystals.

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“…Since the discovery of icosahedral Al±Mn quasicrystals in 1984 (Shechtman et al, 1984), much attention has been focused on approximants related to icosahedral or decagonal quasicrystals (Bendersky, 1987;Shoemaker et al, 1989;Le Lann & Shoemaker, 1993;Kreiner & Franzen, 1995). Their structures are periodic and locally similar to those of quasicrystals.…”

Section: Introductionmentioning

confidence: 99%

“…The "-Al 4 Mn phase is one of the approximants in the Al±Mn system and has a composition close to those of icosahedral and decagonal quasicrystals (Bendersky, 1987;Shoemaker et al, 1989;Le Lann & Shoemaker, 1993). It gives EDPs similar to those of icosahedral and decagonal quasicrystals (Bendersky, 1987), and its structure with a large hexagonal unit cell (P6 3 /mmc, a = 19.98, c = 24.673 A Ê ) has been determined by Shoemaker et al (1989); they used it to deduce structure models of the icosahedral quasicrystal in the Al±Mn system (Le Lann & Shoemaker, 1993). Kreiner & Franzen (1995) have described the structure of the "-Al 4 Mn phase based on the cluster concept.…”

Section: Introductionmentioning

confidence: 99%

The structure of the decagonal approximant Al 3 Mn interpreted as a modulated crystal

Uchida¹,

Matsui²

2002

Philosophical Magazine A

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The structure of the decagonal approximant Al 3 Mn phase, which has been described in terms of the aggregation of clusters until now, is interpreted as a modulated crystal structure. It contains everywhere the same stacking motif as observed in icosahedral approximants such as the m-and l-Al 4 Mn phases as reported by Uchida and Matsui (2000, Acta crystallogr., B, 56, 654) and is suggested to be a crystal subjected to a shear transformation on the unit-cell scale.} 1. Introduction Much attention has been focused on approximants related to icosahedral and decagonal quasicrystals. Their structures are periodic and locally similar to those of quasicrystals. Their electron diOE raction patterns (EDPs) are very similar to those of quasicrystals. The approximants have played important roles in understanding the atomic arrangements in quasicrystals.The Al 3 Mn phase is one of the decagonal approximants and has a composition close to that of the decagonal quasicrystal in the Al±Mn system (Fitz Gerald et al. 1988, Daulton et al. 1991, Li et al. 1992, Hiraga et al. 1993. It gives EDPs similar to those of the decagonal quasicrystal, and its structure with an orthorhombic unit cell (Pnma; aˆ1:483 nm, bˆ1:243 nm and cˆ1:251 nm) has been determined by the single-crystal X-ray diOE raction method (Hiraga et al. 1993a, Shi et al. 1994 and described in terms of the aggregation of clusters (Hiraga et al. 1993, Shi et al. 1994. Hiraga and Sun (1993) and Li (1995) have used it to deduce the structure models of decagonal quasicrystals with a periodicity of 1.2 nm along the tenfold axis.Recently, we presented a new interpretation of the structure of the icosahedral approximant m-Al 4 Mn phase as a modulated crystal (Uchida and Horiuchi 1999). It was shown that the structure is basically composed of close-packed layers with ordered atomic vacancies because of the occurrence of charge-density waves. Our interpretation is essentially diOE erent from the idea of packing clusters in the following respect: the existence of a basic structure with long-range translational periodicity such as a close-packed layer. We applied our interpretation without clusters to several icosahedral approximants such as the l-Al 4 Mn phase and the e-Al 4 Cr phase

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Three-dimensional model of structural transformation from icosahedral to hexagonal structure (μAl4Mn)

Cited by 11 publications

References 6 publications

Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Molecular dynamics investigation of a one-component model for the stacking motif in complex alloy structures

The structure of the decagonal approximant Al 3 Mn interpreted as a modulated crystal

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Three-dimensional model of structural transformation from icosahedral to hexagonal structure (μAl4Mn)

Cited by 11 publications

References 6 publications

Crystal structure of the orthorhombic Al4(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Crystal structure of the orthorhombic Al4(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Molecular dynamics investigation of a one-component model for the stacking motif in complex alloy structures

The structure of the decagonal approximant Al 3 Mn interpreted as a modulated crystal

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Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal

Crystal structure of the orthorhombic Al₄(Cr,Fe) approximant of the Al–Cr–Fe decagonal quasicrystal