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Icosahedral clusters, icosahedral order and stability of quasicrystals - a view of metallurgy.
- This is a scientific article, which reviews the stability of various icosahedral quasicrystals (iQc) from a metallurgical viewpoint. The stability of stable iQcs is well interpreted in terms of Hume-Rothery rules, i.e. atomic size factor and valence electron concentration, e/a. For metastable iQcs, the role of phason disorder introduced by rapid solidification, in structural stability and its interplay with chemical order and composition is discussed. The article is publshed in Sci. Technol. Adv...
- Creator: An Pang Tsai, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai
- Keywords: stable quasicrystal • isodahedral cluster • valence concentration • phason disorder • icosahedral order • metallurgy
- Date added: 10 October 2011
Icosahedrite, Al₆₃Cu₂₄Fe₁₃, the first natural quasicrystal
- This is a scientific article, which introduces Icosahedrite, ideally Al63Cu24Fe13, a new mineral from the Khatyrka River, southeastern Chukhotka, Russia. Icosahedrite is opaque with a metallic luster, possesses a gray streak, and is brittle with an uneven fracture. For quasicrystals, by definition, the structure is not reducible to a single three-dimensional unit cell, so neither cell parameters nor Z can be given. The X-ray powder pattern was indexed on the basis of six integer indices, as conv...
- Creator: Paul J. Steinhardt, Princeton Center for Theoretical Science, Princeton University, Princeton • Luca Bindi, NR-Istituto di Geoscienze e Georisorse, Sezione di Firenze, Firenze • Nan Yao, Princeton Institute for the Science and Technology of Materials, Princeton University • Peter J. Lu, Department of Physics and SEAS, Harvard University, Cambridge, Massachusetts
- Keywords: icosahedrite • mineral • natural quasicrystal • electron-microprobe • reflectance • X-ray diffraction • Al-Cu-Fe • atomic structure • Kamchatka
- Date added: 10 October 2011
Al-Ni-Co quasicrystal bar
- This photograph shows decagonal bar morphology of a Al-Ni-Co quasicrystal. The flux growth technique appears to be a powerful and versatile tool to prepare most of the known quasicrystal systems. The single-grain samples resulting from such growths are large, very well-ordered, strain-free, and show no evidence of secondary phases....
- Creator: Paul Canfield, AMES Laboratory, US Department of Energy • Paul Canfield, AMES Laboratory, US Department of Energy
- Keywords: decagonal • flux grow • Zn-Mg-Ho • quasicrystal
- Date added: 06 October 2011
Atomic model of Al-Ag quasicrystal
- This image presents an atomic model for a fivefold icosahedral Al-Ag quasicrystal. The model was developed for studying island nucleation on a quasicrystal surface. The model is a tool for potential use for self-growth of quasicrystals; studying unnatural atomic structures in islands, and quasiperiodic arrays of quantum dots....
- Creator: J.W. Evans, AMES Laboratory, US Department of Energy
- Keywords: atomic structure • Al-Ag • quasicrystal • quantum dots • self-growth • island nucleation
- Date added: 05 October 2011
Zn-Mg-Ho quasicrystal
- This micrograph is an electron diffraction pattern of an icosahedral Zn-Mg-Ho quasicrystal....
- Creator: Materialscientist,
- Keywords: electron diffraction • diffraction pattern • Zn-Mg-Ho • quasicrystal
- Date added: 05 October 2011
Zn-Mg-Ho icosahedral quasicrystal
- This photograph shows a single-grain icosahedral Ho-Mg-Zn quasicrystal grown from the ternary melt: by using the self-flux method (excess Mg), and slowly cooling from 700°C to 480°C. The R-Mg-Zn family is the first rare-earth containing quasicrystal structure, which allows the study of localized magnetic moments in a quasiperiodic environment. Shown over a mm scale, the edges are 2.2 mm long. Note the clearly defined pentagonal facets, and the dodecahedral morphology. Published in Phys....
- Creator: Paul Canfield, AMES Laboratory, US Department of Energy • Paul Canfield, AMES Laboratory, US Department of Energy
- Keywords: icosahedral • self-flux method • Zn-Mg-Ho • quasicrystal
- Date added: 05 October 2011
Professor Dan Shechtman on Quasicrystals
- Interview with Technion Distinguished Professor Dan Shechtman of the Faculty of Materials Engineering. Prof. Shechtman is the 2011 Nobel Laureate in Chemistry. Prof. Shechtman shares his story of discovery of a new form of matter. Film made by the American Technion Society....
- Creator: Technion - Israel Institute of Technology
- Keywords: Dan Shechtman • video • quasicrystals • interview • nobel prize • chemistry • 2011 • Technion • Israel Institute of Technology
- Date added: 05 October 2011
Decagonal and Quasi-Crystalline Tilings in Medieval Islamic Architecture
- This is a scientific article, which shows that by 1200 C.E. a conceptual breakthrough occurred in medieval Islamic architecture, in which girih patterns were reconceived as tessellations of a special set of equilateral polygons ("girih tiles") decorated with lines. These tiles enabled the creation of increasingly complex periodic girih patterns, and by the 15th century, the tessellation approach was combined with self-similar transformations to construct nearly perfect quasi-crystalline Penrose...
- Creator: Paul J. Steinhardt, Princeton Center for Theoretical Science, Princeton University, Princeton • Peter J. Lu, Department of Physics and SEAS, Harvard University, Cambridge, Massachusetts
- Keywords: Penrose tiling • girih pattern • polygon • non-periodic • crystal structure • quasicrystal
- Date added: 10 October 2011
Penrose Tiling
- This picture shows a pattern for Penrose tiling, which was constructed using the Penrose substitution rule: the projection is from a lattice in five dimensions to the plane. A Penrose tiling is a non-periodic tiling generated by an aperiodic set of prototiles named after Sir Roger Penrose, who investigated these sets in the 1970s. The aperiodicity of the Penrose prototiles implies that a shifted copy of a Penrose tiling will never match the original. Eventually, it emerged that the atoms in tqua...
- Creator: Edmund Harriss, University of Arkansas
- Keywords: Penrose tiling • five-fold • non-periodic • crystal structure • quasicrystal
- Date added: 06 October 2011

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