INTRODUCTION TO ICOSAHEDRAL QUASICRYSTALS

Quasicrystals ◽  
2000 ◽  
Author(s):  
D. GRATIAS ◽  
M. QUIQUANDON ◽  
A. KATZ
Keyword(s):  
Icosahedral Quasicrystals

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

Optical properties of icosahedral quasicrystals

2020 ◽  
Author(s):  
Artem Sinelnik ◽  
Ivan Shishkin ◽  
Xiaochang Yu ◽  
Kirill Samusev ◽  
Pavel Belov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Icosahedral Quasicrystals

Indexing approximants of icosahedral quasicrystals

1999 ◽  
Vol 55 (6) ◽  
pp. 975-983 ◽  
Author(s):  
M. Quiquandon ◽  
A. Katz ◽  
F. Puyraimond ◽  
D. Gratias
Keyword(s):  
Unit Cell ◽  
Dimensional Lattice ◽  
Geometrical Properties ◽  
Actual Model ◽  
Icosahedral Quasicrystals ◽  
Low Dimensional

It is well known that the crystallography of approximants is directly related to that of the parent quasicrystal, once its unit-cell vectors are identified as parallel projections of certain N-dimensional lattice nodes {\bf A}^{i}. Derived here are explicit simple relations for calculating the shear matrices {\boldvarepsilon} and the related crystallographic properties of the corresponding approximants, including diffraction indexing and the determination of the lattice in perpendicular space. Applied to low-dimensional approximants, the derivation shows that the systematic `accidental' extinction rules observed in the pentagonal phases are generic extinctions that are due to the geometrical properties of the projected 1D lattice and are independent of the actual model of the quasicrystal.

Cleavage Planes of Icosahedral Quasicrystals: A Molecular Dynamics Study

2003 ◽  
Vol 805 ◽  
Author(s):  
Frohmut Rösch ◽  
Christoph Rudhart ◽  
Peter Gumbsch ◽  
Hans-Rainer Trebin
Keyword(s):  
Molecular Dynamics ◽  
Brittle Fracture ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Propagation Direction ◽  
Mode I ◽  
Dynamic Crack ◽  
Fracture Surfaces ◽  
Icosahedral Quasicrystals ◽  
Crack Tip Plasticity

ABSTRACTThe propagation of mode I cracks in a three-dimensional icosahedral model quasicrystal has been studied by molecular dynamics techniques. In particular, the dependence on the plane structure and the influence of clusters have been investigated. Crack propagation was simulated in planes perpendicular to five-, two- and pseudo-twofold axes of the binary icosahedral model.Brittle fracture without any crack tip plasticity is observed. The fracture surfaces turn out to be rough on the scale of the clusters. These are not strictly circumvented, but to some extent cut by the dynamic crack. However, compared to the flat seed cracks the clusters are intersected less frequently. Thus the roughness of the crack surfaces can be attributed to the clusters, whereas the constant average heights of the fracture surfaces reflect the plane structure of the quasicrystal. Furthermore a distinct anisotropy with respect to the in-plane propagation direction is found.

Self-diffusion of manganese in AlPdMn icosahedral quasicrystals

1994 ◽  
Vol 181-182 ◽  
pp. 738-741 ◽  
Author(s):  
H Nakajima ◽  
J Asai ◽  
K Nonaka ◽  
I Shinbo ◽  
A Tsai ◽  
...  
Keyword(s):  
Self Diffusion ◽  
Icosahedral Quasicrystals

Electrical resistivity, thermopower, and thermal conductivity of single grained (Y, Tb, Ho, Er)-Mg-Zn icosahedral quasicrystals

2000 ◽  
Vol 294-296 ◽  
pp. 715-718 ◽  
Author(s):  
K Giannò ◽  
A.V Sologubenko ◽  
M.A Chernikov ◽  
H.R Ott ◽  
I.R Fisher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Icosahedral Quasicrystals
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