Two-dimensional quasicrystal with eightfold rotational symmetry

Wang, Naiyan; Chen, Hanyuan; Kuo, K. H.

doi:10.1103/physrevlett.59.1010

Cited by 329 publications

(137 citation statements)

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“…1(c [ Fig. 4(b) In a previous investigation, we have found that the octagonal quasicrystal coexists with p-Mn-type crystal [7]. The transformation of the octagonal quasicrystal to p-Mn-type crystal structure has been observed and interpreted as due to the gradual introduction of phason strain [21].…”

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“…Quasicrystal thin films were then prepared by remelting and rapid solidification of the alloy by the piston-and-anvil method as reported previously [7]. Specimens for TEM were prepared by ion milling the thin films.…”

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“…In An alloy with nominal composition Mn80Si]&A15 was obtained by melting high-purity manganese, silicon, and aluminum in argon atmosphere in an arc furnace. Quasicrystal thin films were then prepared by remelting and rapid solidification of the alloy by the piston-and-anvil method as reported previously [7]. Specimens Fig.…”

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Direct observation of domains and discommensurations in Mn-Si-Al octagonal quasicrystal by transmission electron microscopy

et al. 1991

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An alloy with nominal composition Mn80Si]&A15 was obtained by melting high-purity manganese, silicon, and aluminum in argon atmosphere in an arc furnace. Quasicrystal thin films were then prepared by remelting and rapid solidification of the alloy by the piston-and-anvil method as reported previously [7]. Specimens for TEM were prepared by ion milling the thin films. A Philips EM 420 electron microscope was employed for taking electron-diAraction patterns and images.The Mn-Si-Al octagonal quasicrystal is a two-dimensional quasicrystal with a periodic eightfold axis (A8) and sixteen orthogonal twofold axes (e.g. , A2P and A2D), as shown in Fig. 1

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Direct observation of domains and discommensurations in Mn-Si-Al octagonal quasicrystal by transmission electron microscopy

et al. 1991

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“…6,7 The two-dimensional octagonal quasicrystal is a metastable phase which was found in Cr-Ni-Si, V-Ni-Si, Mn-͑Si, Al͒ alloy systems. [8][9][10] In a previous study, the symmetry of an octagonal quasicrystal was determined to be 8/mmm or 8/m. 11 Transmission electron microscopic ͑TEM͒ observations showed that 45°microtwin domains of ␤-Mn-type structure coexisted with the octagonal phase in Mn-Si-Al and Cr-Ni-Si alloys, indicating that these structures were closely related.…”

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Electron diffraction study of octagonal-cubic phase transitions in Mn-Si-Al

Wang

Lee

et al. 2000

Phys. Rev. B

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We report the observation of two kinds of octagonal-cubic transition to either the ␤-Mn-type structure or the Mn 3 Si crystal following annealing Mn-Si-Al octagonal quasicrystal at different heating speeds. A theoretical analysis has been given and the simulated diffraction patterns match the experimental results well. It is confirmed that there exist two kinds of phason strain fields, which transform the octagonal phase into the two cubic crystalline phases, respectively. It is conjectured that the octagonal-cubic transitions feature the formation of local periodic structures.Since the experimental discovery of icosahedral quasicrystals, 1 a number of different quasicrystals have been prepared and studied. Furthermore, many periodic structures closely related to quasicrystals have been discovered. 2 Because they have local atomic structures and chemical composition similar to the related quasicrystals, these kinds of materials are named the ''approximants'' of quasicrystals. In experiments, quasicrystalline phases often coexist with their approximant phases, and reversible transformations between quasicrystals and their approximants have been observed. For instance, it has been reported that the AlCuCoSi decagonal phase transforms to a microcrystalline state of a ͑5, 7͒ approximant at lower temperature, and vice versa. 3 In this case, there is not a smooth shift of diffraction peak positions between those of the approximant and those of the decagonal quasicrystal, but instead, there is a coexistence of the two sets of peaks with changes in relative intensities through the phase transition. On the other hand, in rapidly solidified AlMnSi and AlCrSi alloys intermediate structures during the transformation of a decagonal quasicrystal to tenfold twins of a crystalline structure have been observed. 4 Experimental electron diffraction patterns shows the continuous shift of spots from the quasicrystal to the B-centered orthorhombic phase through the intermediate stages.Approximant structures can be described by the so-called ''strip-rotation'' projection scheme, 5 the projected strip in the higher-dimensional space is rotated away from the original one generating the quasiperiodic tiling so that the rotated strip is rational with respect to the higher-dimensional lattice. In general, the quasicrystal structure can be considered as the limit of sequence of periodic structures with the increasing unit cells of the approximants. Moreover, this kind of distortion of the system is induced by the phason strain field, the phason degrees of freedom associated with translations in the perpendicular space. Therefore the transformation from the quasicrystal to the approximant can be explained to be of phason-type. 6,7 The two-dimensional octagonal quasicrystal is a metastable phase which was found in Cr-Ni-Si, V-Ni-Si, Mn-͑Si, Al͒ alloy systems. [8][9][10] In a previous study, the symmetry of an octagonal quasicrystal was determined to be 8/mmm or 8/m. 11 Transmission electron microscopic ͑TEM͒ observations showed that 45°microt...

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“…Regions with large differences in the densities of DCs have also been observed. As in the case of the Mn-Si-Al octagonal quasicrystal, the Mo-Cr-Ni alloy obtained by melting the high-purity elements in argon atmosphere in an arc furnace was remelted and then solidified rapidly in the form of thin films using the piston-and-anvil method as reported previously [6]. Specimens for study in a Philips EM 420 electron microscope were prepared by ion milling the thin films to electron transparency.…”

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