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.

Hierarchical Design and Nanomechanics of the Calcified Byssus of Anomia simplex

2009 ◽  
Vol 1187 ◽  
Author(s):  
Jakob R Eltzholtz ◽  
Marie Krogsgaard ◽  
Henrik Birkedal
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Mechanical Performance ◽  
Blue Mussel ◽  
Hierarchical Design ◽  
Reduced Modulus ◽  
Different Types ◽  
Microscopy Images ◽  
Scanning Electron

AbstractBiology has evolved several strategies for attachment of sedentary animals. In the bivalves, byssi abound and the best known example being the protein-based byssus of the blue mussel and other Mytilidae. In contrast the bivalve Anomia sp. has a single calcified thread. The byssus is hierarchical in design and contains several different types of structures as revealed by scanning electron microscopy images. The mechanical properties of the byssus are probed by nanoindentation. It is found that the mineralized part of the byssus is very stiff with a reduced modulus of about 67 GPa and a hardness of ˜3.7 GPa. This corresponds to a modulus roughly 20% smaller than that of pure calcite and a hardness that is about 20% larger than pure calcite. The results reveal the importance of microstructure on mechanical performance.

Local Structural Variations in Al72Ni20Co8 Decagonal Quasicrystals

2003 ◽  
Vol 805 ◽  
Author(s):  
Yanfa Yan ◽  
S. J. Pennycook
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Total Energy ◽  
First Principles ◽  
Density Functional ◽  
High Resolution Electron Microscopy ◽  
Structural Variations ◽  
Decagonal Quasicrystals ◽  
Resolution Electron ◽  
Microscopy Images

ABSTRACTWe investigate local structural variations in Al72Ni20Co8 quasicrystals using first principles density-functional total-energy calculations. We find that local chemical fluctuation can cause large structural variations on the central rings of the 2-nm clusters. Such structure variations may result in ambiguities at the central rings in high-resolution electron microscopy images of Al72Ni20Co8 decagonal quasicrystals.

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.

Unifying cluster-based structure models of decagonal Al–Co–Ni, Al–Co–Cu and Al–Fe–Ni

2011 ◽  
Vol 67 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Sofia Deloudi ◽  
Frank Fleischer ◽  
Walter Steurer
Keyword(s):  
Electron Microscopy ◽  
Symmetry Group ◽  
Electron Density ◽  
Decagonal Quasicrystals ◽  
Density Maps ◽  
Microscopy Images

The geometrical building principles of Al-based decagonal quasicrystals and their approximants are discussed from a cluster-based approach. Our investigations cover 11 modifications with two- or four-layer periodicity in the systems Al–Co–Ni, Al–Co–Cu and Al–Fe–Ni. We identified a cluster that leads to a unifying view of all these phases. This unit cluster has ∼ 20 Å diameter, four-layer periodicity along its tenfold axis and rod symmetry group p \overline{10}2m. The models obtained are in agreement with all the electron-density maps and electron-microscopy images available.

Decomposition of YBa2Cu3O7−x during annealing in CO2/O2 mixtures

1990 ◽  
Vol 5 (7) ◽  
pp. 1363-1367 ◽  
Author(s):  
Y. Gao ◽  
K. L. Merkle ◽  
C. Zhang ◽  
U. Balachandran ◽  
R. B. Poeppel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Reaction Products ◽  
The Third ◽  
Transmission Electron ◽  
Island Type ◽  
Different Types ◽  
The Stability ◽  
Microscopy Images

The stability of YBa2Cu3O7−x superconductors toward reactions with CO2 in CO2/O2 gas mixtures has been studied during annealing at temperatures ranging from 600°C to 950°C. The results show that there are three different types of the reactions. The reaction products of these reactions all include BaCO3 and CuO, while the third product is dependent on the annealing temperature. At 600°C, YBa-carbonates were formed while Y2Cu2O5 and Y2BaCuO5 were formed at 815°C and 950°C, respectively. Transmission Electron Microscopy images show that the reactions started at grain boundaries with the formation of island-type precipitates.

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.

Scanning electron microscopy of asbestos-containing material where the asbestos fibers are considered locked in a binder

1993 ◽  
Vol 51 ◽  
pp. 472-473
Author(s):  
J. R. Millette ◽  
R. S. Brown
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Protection Agency ◽  
Building Materials ◽  
The United States ◽  
Protection Agency ◽  
Asbestos Fibers ◽  
Different Types ◽  
Binder Material ◽  
Scanning Electron

The United States Environmental Protection Agency (EPA) has labeled as “friable” those building materials that are likely to readily release fibers. Friable materials when dry, can easily be crumbled, pulverized, or reduced to powder using hand pressure. Other asbestos containing building materials (ACBM) where the asbestos fibers are in a matrix of cement or bituminous or resinous binders are considered non-friable. However, when subjected to sanding, grinding, cutting or other forms of abrasion, these non-friable materials are to be treated as friable asbestos material. There has been a hypothesis that all raw asbestos fibers are encapsulated in solvents and binders and are not released as individual fibers if the material is cut or abraded. Examination of a number of different types of non-friable materials under the SEM show that after cutting or abrasion, tuffs or bundles of fibers are evident on the surfaces of the materials. When these tuffs or bundles are examined, they are shown to contain asbestos fibers which are free from binder material. These free fibers may be released into the air upon further cutting or abrasion.

A Transmission Electron Microscopical Investigation of Phase Transformations in TiNi

1980 ◽  
Vol 38 ◽  
pp. 340-341
Author(s):  
P. Moine ◽  
G. M. Michal ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Applied Stress ◽  
Structural Changes ◽  
Microscopical Investigation ◽  
Temperature Range ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Diffraction Effects ◽  
Microscopy Images

Premartensitic effects in near equiatomic TiNi have been pointed out by several authors(1-5). These include anomalous contrast in electron microscopy images (mottling, striations, etc. ),diffraction effects(diffuse streaks, extra reflections, etc.), a resistivity peak above Ms (temperature at which a perceptible amount of martensite is formed without applied stress). However the structural changes occuring in this temperature range are not well understood. The purpose of this study is to clarify these phenomena.

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