……………………..Limits are for governments.

“Crystals of Golden Proportions”

Figure 1. Dan Shechtman’s diffraction pattern of a quasicrystal, previously thought to be an impossible or forbidden symmetry - for which he won the 2011 Nobel Prize in Chemistry.

‘“Eyn chaya kazo”, Dan Shechtman said to himself. “There can be no such creature” in Hebrew. It was the morning of 8 April 1982. The material he was studying, a mix of aluminum and manganese, was strange looking, and he had turned to the electron microscope in order to observe it at the atomic level. However, the picture that the microscope produced was counter to all logic: he saw concentric circles, each made often bright dots at the same distance from each other (figure 1).

Shechtman had rapidly chilled the glowing molten metal, and the sudden change in temperature should have created complete disorder among the atoms. But the pattern he observed told a completely different story: the atoms were arranged in a manner that was contrary to the laws of nature. Shechtman counted and recounted the dots. Four or six dots in the circles would have been possible, but absolutely not ten. He made a notation in his notebook: 10 Fold???”‘

~read more here:  http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2011/popular-chemistryprize2011.pdf

Comment: At first, Dr. Shechtman was rediculed for his “impossible” discovery, and given a textbook on crystallography to study. Eventually, his boss asked him to leave the research group. But as his paper gained some circulation and the results were repeated, he was vindicated for believing the observations, rather than the textbooks.

You see, things really do turn out right in science sometimes!

4 responses

  1. Interesting, the paper describes points of energy to create the visual points of light where the energy bands cross. The picture is not of the actual crystal structure but of the maximum energy points of the electron shells interface between crystals. pg

    February 15, 2012 at 11:02 pm

  2. Yes, it is a diffraction of a stream of electrons through the crystal.

    Now to find where these crystals occur in nature. So far I found one article about a Russian meteorite grain that has a quasicrystal. There is another article about the possiblility of water crystals forming in this way, but only based on modeling. Cheers PG. (:

    February 16, 2012 at 7:16 pm

  3. Topological behaviour spotted in quasicrystal

    Sep 11, 2012 4 comments

    When 1D looks like 2D

    A surprising connection between quasicrystals and topological insulators has been demonstrated in the lab by physicists in Israel. The team has studied how light propagates through a 1D quasicrystal and found that it is similar to how electrons conduct in a 2D topological insulator. The surprising result suggests that quasicrystals could be used to create systems with dimensionality higher than 3D – something that could be useful both in studying fundamental physics and creating materials with new and useful properties.

    A topological insulator is a material that is an insulator in the bulk but for reasons related to geometry is a conductor on its surface or edge. Perhaps the most famous example of a topological insulator is the integer quantum Hall effect (IQHE), whereby electrons on the edges of a 2D ribbon conduct electricity but no conduction occurs in the middle (or bulk) of the ribbon. Now Yaacov Kraus, Oded Zilberberg and colleagues at Israel’s Weizmann Institute of Science have shown that a similar 2D topological effect can be seen in how light propagates in a 1D quasicrystal – suggesting that the quasicrystal actually has 2D topology.

    The team performed experiments using 2D arrays of parallel waveguides. The separation between the waveguides is set so that some of the light propagating down one waveguide can leak into an adjacent waveguide, then into the next and so forth (see figure). If the movement of the light in the direction perpendicular to the waveguides is considered, it is similar to an electron moving through a 1D lattice with lattice spacing equal to the distance between the waveguides. The fact that the light “hops” from one waveguide to the next makes the system analogous to a model of electron conduction.

    Sticking to the edge

    In one experiment the team created a system in which the optical properties of the waveguides – and the spacing between them – are not identical. Instead, the structure is actually a quasicrystal described by the Aubry–André (AA) model. When a pulse of light is fired into a waveguide in the centre of the quasicrystal it spreads out to adjacent waveguides as it propagates through. However, when a pulse is fired at the waveguide at the left edge of the quasicrystal all the light remains in that channel, which the team say is a “clear signature of the existence of a localized boundary state”.

    In the next experiment the team focused on an effect called “adiabatic pumping”, whereby light is transferred from one edge of a device to the other – a topological effect that is seen in materials that exhibit the IQHE. To see this pumping the team created a second quasicrystal based on a different version of the AA model. When a light pulse is introduced to a waveguide at the edge of the device the light migrates across the device with all of it ending up in the waveguide at the opposite edge (see figure). So once again, a 1D quasicrystal seems to behave in the same way as a system with 2D topology.

    The physicists explain this curious behaviour by pointing out that the AA model contains a parameter that provides a mathematical description of the quasicrystal. This, they argue, can be thought of as an extra dimension – effectively boosting the topology to 2D.

    According to Kraus, this discovery is exciting because it means that systems with topologies beyond 3D could be created using quasicrystals – something that would be a boon for fundamental physics. Also, it could be possible to use quasicrystals to create practical devices based on materials with specific topologies.

    The team is now looking at how to create a 2D quasicrystal with 4D topology.

    The research is described in Physical Review Letters.

    About the author

    Hamish Johnston is editor of physicsworld.com


    Add your comments on this article


    John DuffieldSep 12, 2012 9:22 AM United Kingdom

    Good research, good reporting. I think this sort of thing could also be important to fundamental physics because it may shed light (ho!) on the nature of the photon and the nature of the electron. After all, you can make an electron, and a positron, out of a photon in pair production, so IMHO saying “it’s a fundamental particle” surely isn’t enough. All this makes me wonder why Topological Quantum Field Theory doesn’t seem to be at the forefront of particle physics any more, though that just might be my mistaken impression.
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    reader01Sep 12, 2012 9:49 AM

    I can not imagine

    to what all matterials with 3D and more dimensions can lead. But I have maybe a little smilling idea of 4D and more D tranzistor. This is that I think that some new technology must in future be here instead of classical tranzistor technology. Maybe more D tranzistor can strenthen ellectric currant in more dimensions and thus replace more common tranzistors. And this can be the same with many other things that can be possibly replaced by new one. This article is one of best I read here in this month.
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    M. AsgharSep 12, 2012 10:12 AM

    Good start that needs sharpening

    ID quasicrytal is is collection of points lying on a line spread quasiperiodically.Here, the team created and worked with different types of ID quasicrystal using 2D arrrays of parallel waveguides. The results seem to indicate the 2D topolgical nature of 1D quasicrystal: light entering the system at one edge and coming out at the other edge due to the topological constraints. This indicates that for a 3D quasicrytal, one should be able to study its higher 4D topological properties.
    It is intersting to confront this possibilty with the holographic principle used in cosmology, where lower dimension is important: the entropy of a 3D-object is proprtional to its 2D-surface.
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    M. AsgharSep 13, 2012 8:34 AM

    Question to Dr. Johnston

    Dr. Johnston, the team of this work found that
    1. 1D-quasicrytal is equivalent to a 2D-topological insulator with the electron-conducting levels around its edges,
    2. 2D-quasicrystal should be equivalent to a 3D-topolgical insulator with conduction levels on its surface,
    3. If a 3D-quasicrystal should be equivalent to a 4D-topological insulator, where will one place its conduction levels? The team seems to be working on this thing. Your effort to clarify this point will be appreciated.

    September 13, 2012 at 4:41 pm

  4. Here is a patent held by Dr. Orest G. Symko of the University of Utah in applications for quasicrystalline alloys applied through radio frequencies. He also does research into the electrical , optical, and mechanical properties of quasicrystalline thin films using stainless steel, silicon, sapphire, quartz, and glass.

    Various articles of manufacture, such as electrosurgical scalpels, razor blades, and electronic components, comprise a quasicrystalline AlCuFe alloy film less than about 3000 Å thick, formed by depositing in sequence on a substrate through radio frequency sputtering a stoichiometric amount of each respective alloy material and then annealing those layers to form the film through solid state diffusion.



    January 24, 2013 at 3:26 pm

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