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Daniel Shechtman |
Daniel Shechtman
Technion - Israel Institute of Technology, Haifa, Israel
In quasicrystals, we find the fascinating mosaics of
the Arabic world reproduced at the level of atoms: regular patterns that
never repeat themselves. However, the configuration found in
quasicrystals was considered impossible, and Daniel Shechtman had to
fight a fierce battle against established science. The Nobel Prize in
Chemistry 2011 has fundamentally altered how chemists conceive of solid
matter.
On the morning of 8 April 1982, an image counter to the laws of
nature appeared in Daniel Shechtman's electron microscope. In all solid
matter, atoms were believed to be packed inside crystals in symmetrical
patterns that were repeated periodically over and over again. For
scientists, this repetition was required in order to obtain a crystal.
Shechtman's image, however, showed that the atoms in his crystal were
packed in a pattern that could not be repeated. Such a pattern was
considered just as impossible as creating a football using only
six-cornered polygons, when a sphere needs both five- and six-cornered
polygons. His discovery was extremely controversial. In the course of
defending his findings, he was asked to leave his research group.
However, his battle eventually forced scientists to reconsider their
conception of the very nature of matter.
Aperiodic mosaics, such as those found in the medieval Islamic
mosaics of the Alhambra Palace in Spain and the Darb-i Imam Shrine in
Iran, have helped scientists understand what quasicrystals look like at
the atomic level. In those mosaics, as in quasicrystals, the patterns
are regular - they follow mathematical rules - but they never repeat
themselves.
When scientists describe Shechtman's quasicrystals, they use a
concept that comes from mathematics and art: the golden ratio. This
number had already caught the interest of mathematicians in Ancient
Greece, as it often appeared in geometry. In quasicrystals, for
instance, the ratio of various distances between atoms is related to the
golden mean.
Following Shechtman's discovery, scientists have produced other kinds
of quasicrystals in the lab and discovered naturally occurring
quasicrystals in mineral samples from a Russian river. A Swedish company
has also found quasicrystals in a certain form of steel, where the
crystals reinforce the material like armor. Scientists are currently
experimenting with using quasicrystals in different products such as
frying pans and diesel engines.For more details click here..
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