Researchers at Tel Aviv University have deciphered the secret to the stability of quasicrystals, similar to those whose discoveries earned Prof. Dan Shechtman of the Technion the 2011 Nobel Prize in Chemistry
In 1982, the Israeli scientist Dan Shechtman discovered a phenomenon that until then was considered scientifically impossible: non-periodic crystals. Until that time, scientists believed that the atoms that make up the crystals were always arranged in a cyclic manner, similar to the square squares on the chessboard or the hexagonal cells in the honeycomb. Prof. Shechtman's revolutionary discovery proved that this is not necessarily the case and earned him the Nobel Prize in Chemistry 30 years later. Most crystals of the type Shechtman discovered, called quasi-periodic crystals or quasi-crystals for short, are solid metallic alloys. Recently, quasi-crystals were discovered made of soft materials consisting of very large and flexible molecules - those that can relatively easily change their size and shape - and the question arose as to whether it is possible to design these molecules and get any crystal you want.
In a new article published in the journal Physical Review Letters, researchers from Tel Aviv University, led by Prof. Ron Lifshitz from the School of Physics and Astronomy, in collaboration with their colleague Michael Engel from the University of Michigan in the USA, demonstrated how this can be done. They developed a new method to design and control the formation of soft crystals, periodic or non-periodic, with a variety of different structures and symmetries. In the future, the method may lead to innovative developments, including materials with advanced optical properties.
instruct the molecules how to arrange themselves when the material crystallizes
"We are dealing with soft materials consisting of large and flexible molecules, like sponge balls with long hairs," explains Prof. Lipshitz. "We asked ourselves whether by simply planning the size of the 'ball' and the length of the 'hairs' we could make the molecules line up as we wanted while they were forming."
Together with research student Kobi Barkan and Prof. Haim Diment from the School of Chemistry, the researchers built a mathematical model for the crystallization process of these soft materials, and deciphered the secret of the stability of the formed crystals - both periodic and non-periodic. Now, based on this mathematical theory, the researchers designed molecules in different shapes and let the computer simulate the crystallization process to see which crystal would result. "We were happy to discover," says Kobi Barkan, "that we always got the crystal we wanted. We know how to design periodic crystals with four-fold and six-fold symmetry, as well as quasicrystals with ten-fold and twelve-fold symmetry." The researchers predict that in the future it will be possible to use their method to produce soft crystals with innovative properties, literally 'to order'.
"Crystals made of soft materials consisting of large molecules are particularly suitable for the production of 'supermaterials' or 'metamaterials' (metamaterials) - engineered materials with unique properties, which are not found in nature in this form. "Due to the size of the molecules corresponding to the wavelength of visible light, there is potential for the development of materials with advanced optical properties," Prof. Lipshitz concludes. "Usually it is necessary to produce these materials artificially using advanced and expensive means of nanotechnology. Our crystals grow on their own, but it looks like we're guiding the molecules how to get along."
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Maya
You made the important point. If you found something real, and the experiment can be reproduced, then in the end the scientific community will accept it. You have to remember that scientists are people...
Hello to Eyal and Miracles,
There were definitely people who saw the quasi-crystals, maybe even before, but certainly after Schechtman. At that time there was a well-established theory in crystallography which stated that the only possible rotational symmetries are 2,3,4,6, while Shechtman's crystals had rotational symmetry of order 5. This fact made scientists very skeptical. In addition, there was, of course, the strong opposition of Linus Pauling, one of the strongest people in the field of chemistry, to the matter of quasi-crystals and in fact it was difficult for the scientist to say that he agreed with quasi-crystals until Pauling's death in 94 (before that, there was a fear of upsetting him...) in any case, The skepticism of the scientists gradually faded as they saw that indeed the results were reproducible and repeated by different scientists.
Regarding why he received a Nobel Prize, I do not know (because I am not at the head of the Nobel Prize Committee) but if I had to guess I would say it is because of the following two reasons:
1. He insisted on the correctness of his discovery even when the scientific community did not accept him.
2. He gathered theorists around him who gave a theoretical explanation to the crystals he found and expanded the existing theory. Although he did not develop the theory himself, the development would not have been possible without his discovery and without his insistence.
This story is much loved by critics of science as an example of the "closed-mindedness" of the scientific community and its inability to accept observations that contradict the paradigms. It's a bit funny because this story describes exactly the ability of the scientific community to accept new ideas that advance science and even award them a Nobel Prize. True, it is not easy to introduce a new concept, as everywhere (scientists are people too) and it has a lot to do with the fact that most new concepts are simply not correct. But when there is a new concept supported by evidence in such a clear way, it will definitely be accepted by the community (and not in such a long time, the discovery was in the early 80's).
Eyal
good questions I don't know how to answer them.
Hi Nissim, the story about the two scientists is familiar to me, but still regarding the crystals it seems strange to me... I also don't understand why only Dan Shechtman saw these non-periodic crystals, are they so rare that they were created only in his laboratory and not anywhere else in the world? How is it that no other scientist has come across them before? Maybe part of his research work was a method to create these crystals? (just a wild guess)
Eyal
Regarding the second part - there are many such cases: people who received a Nobel Prize for something that seems small. Penzias Wilson received a Nobel Prize in 1978 for something they thought was pigeon poop…..
I think what is important is the meaning of the discovery and not how much was invested in the discovery itself. In addition, it is very possible that if Penzias Wilson had not insisted on understanding the noise they saw, or had not been so pedantic (professional), years would have passed before they would have discovered the cosmic radiation.
Two main things I still haven't been able to understand about Dan Shechtman's win -
1. Why did it take so long for other scientists to agree to accept the discovery? Couldn't they look through the microscope and see with their own eyes the crystals that Dan Shechtman saw? Why didn't they do it?
2. What did Dan Shechtman receive the award for, that he happened to look at a crystal under a microscope and saw that it was not periodic? What kind of research work was there other than looking at the crystal and saying I see like this and like that? (There is no tone of disrespect here, lest it be misunderstood, this is simply a point that is not clear to me)
Thanks in advance if anyone can answer me.