Nano Atom Clusters and Their Long-Range Quasiperiodic Arrangements in Al-Ni-Ru Decagonal Quasicrystal

2005 ◽  
Vol 475-479 ◽  
pp. 3351-3354
Author(s):  
Wei Sun ◽  
Ze Zhang ◽  
Kenji Hirage
Keyword(s):  
Electron Microscopy ◽  
Long Range ◽  
Structural Features ◽  
Penrose Tiling ◽  
Linear Phase ◽  
Decagonal Quasicrystal ◽  
Wide Region ◽  
Atom Clusters ◽  
Decagonal Quasicrystals ◽  
Quasiperiodic Structure

The structural features of nano-sized atom clusters and their long-rang arrangement in the Al-Ni-Ru decagonal quasicrystal with 1.6 nm periodicity have been studied and compared with those in the Al-Pd-Mn decagonal quasicrystal on the basis of electron microscopy. From the perpendicular-space analysis of the tiling obtained in a wide region, we conclude that long-range arrangement of atom clusters in the Al-Ni-Ru decagonal quasicrystal with 1.6 nm periodicity can form a Penrose-tiling-like quasiperiodic structure which is almost free of linear phase strain. In contrast, the tiling structure of the Al-Pd-Mn decagonal quasicrystal contains heavy phason strain. Our results clearly show that atom clusters formed in the Al-Ni-Ru decagonal quasicrystals and their linkage manner are completely different from those in the Al-Pd-Mn decagonal quasicrystal.

Decagonal random tilings and their quasi-unit cell cluster coverings

2021 ◽  
pp. 2150171
Author(s):  
Juan García Escudero
Keyword(s):  
Electron Microscopy ◽  
Structural Unit ◽  
Cell Cluster ◽  
Penrose Tiling ◽  
Decagonal Quasicrystals ◽  
Different Types ◽  
Complex Structural ◽  
Random Tilings ◽  
Microscopy Images ◽  
Bow Tie

Electron microscopy images of decagonal quasicrystals obtained recently have been shown to be related to cluster coverings with a Hexagon–Bow–Tie decagon as single structural unit. Most decagonal phases show more complex structural orderings than models based on deterministic tilings like the Penrose tiling. We analyze different types of decagonal random tilings and their coverings by a Hexagon–Bow–Tie decagon.

CBED and HREM study of decagonal quasicrystals

1996 ◽  
Vol 54 ◽  
pp. 704-705
Author(s):  
M. Tanaka ◽  
K. Tsuda ◽  
K. Saitoh
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Hrem Image ◽  
Space Group ◽  
Space Groups ◽  
Atom Clusters ◽  
Decagonal Quasicrystals ◽  
Black Circle ◽  
Resolution Electron

Decagonal quasicrystals have been investigated by convergent-beam electron diffraction (CBED) and transmission electron microscopy. Figure 1 shows possible pentagonal and decagonal point groups. The CBED method has revealed that the decagonal quasicrystals found so far belong to the space groups of noncentrosymmetric P10m2 and centrosymmetric P1O5mmc.Dark-field microscopy has revealed the existence of inversion domains with an antiphase shift of c/2 at the domain boundaries in the alloys with space group m2.2 High-resolution electron microscopy (HREM) has revealed the existence of specific pentagonal atom clusters in the Al-Ni-Fe, Al-Cu-Co and Al-Ni-Co alloys. Figure 2 shows a HREM image of Al70Ni15Fe15 belonging to space group m2. The atom clusters of an about 2nm diameter are clearly seen as indicated by a black circle. The clusters are polar or noncentrosymmetric due to the dark pentagon at their centers. All the clusters in domain A have one sense of polarity and those in domain B the other sense. It should be noted that the HREM image of the cluster columns was found to be pentagonal at an accelerating voltage of 200kV but nearly decagonal at higher than 300kV.

scholarly journals Insight into the structure of decagonite – the extraterrestrial decagonal quasicrystal

IUCrJ ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 87-101
Author(s):  
Ireneusz Buganski ◽  
Luca Bindi
Keyword(s):  
Solar System ◽  
Structural Model ◽  
Layer Structure ◽  
Penrose Tiling ◽  
Decagonal Quasicrystal ◽  
X Ray ◽  
Decagonal Quasicrystals ◽  
High Degree ◽  
Insight Into

A set of X-ray data collected on a fragment of decagonite, Al71Ni24Fe5, the only known natural decagonal quasicrystal found in a meteorite formed at the beginning of the Solar System, allowed us to determine the first structural model for a natural quasicrystal. It is a two-layer structure with decagonal columnar clusters arranged according to the pentagonal Penrose tiling. The structural model showed peculiarities and slight differences with respect to those obtained for other synthetic decagonal quasicrystals. Interestingly, decagonite is found to exhibit low linear phason strain and a high degree of perfection despite the fact it was formed under conditions very far from those used in the laboratory.

Transformation of Al–Ni–(Si) decagonal quasicrystals to 1–D quasicrystal and crystalline approximants

1993 ◽  
Vol 8 (10) ◽  
pp. 2499-2503 ◽  
Author(s):  
X.Z. Li ◽  
K.H. Kuo
Keyword(s):  
Electron Microscopy ◽  
Crystalline Phase ◽  
Two Dimensional ◽  
Decagonal Quasicrystal ◽  
One Dimensional ◽  
Decagonal Phase ◽  
Decagonal Quasicrystals ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Orientational Relationship

Rapidly quenched Al86-xNi14Six (x = 0, 2, 6, and 10) alloys have been studied by means of transmission electron microscopy. Two-dimensional (2-D) decagonal quasicrystal with a periodicity of 1.6 nm along its tenfold axis was found in the rapidly quenched Al86Ni14 binary alloy. With the addition of some silicon, such as AlgoNi14Si6, the 2-D decagonal quasicrystal first transforms to a one-dimensional (1-D) quasicrystal that inherits the periodicity along the tenfold axis and has, in addition, translation periodicity in one of the twofold axes of the decagonal phase, and finally transforms to a new orthorhombic crystalline phase (a = 0.78, b = 1.62, and c = 1.48 nm). In the Al76Ni14Si10 ternary alloy, a 2-D decagonal quasicrystal with a periodicity of 0.4 nm and a coexisting crystalline phase with the “Al3Ni2” structure were found, and their orientational relationship has been determined.

Generalized Penrose tiling as a quasilattice for decagonal quasicrystal structure analysis

2015 ◽  
Vol 71 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Maciej Chodyn ◽  
Pawel Kuczera ◽  
Janusz Wolny
Keyword(s):  
Long Range ◽  
Physical Space ◽  
Range Order ◽  
Penrose Tiling ◽  
Long Range Order ◽  
Shift Parameter ◽  
Decagonal Quasicrystal ◽  
Final Formula ◽  
Higher Dimensional ◽  
Average Unit

The generalized Penrose tiling is, in fact, an infinite set of decagonal tilings. It is constructed with the same rhombs (thick and thin) as the conventional Penrose tiling, but its long-range order depends on the so-called shift parameter (s∈ 〈0; 1)). The structure factor is derived for the arbitrarily decorated generalized Penrose tiling within the average unit cell approach. The final formula works in physical space only and is directly dependent on thesparameter. It allows one to straightforwardly change the long-range order of the refined structure just by changing thesparameter and keeping the tile decoration unchanged. This gives a great advantage over the higher-dimensional method, where every change of the tiling (change in thesparameter) requires the structure model to be built from scratch,i.e.the fine division of the atomic surfaces has to be redone.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

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