APS Meeting: Quasicrystal adventures

Mar 27, 2019
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To all those who think being a scientist is not very exciting, Paul Steinhardt today at the American Physical Society meeting in Portland, OR, gave some reasons to think again.

Steinhardt has done lots of work leading to the discovery and characterization of quasicrystals, solids which are ordered but nonperiodic. Created in the lab in the mid ’80s, they have proven to be very hard to spot in nature. About 10 years ago, Steinhardt and his students started analyzing systematically large catalogs of powder diffraction spectra of naturally occurring minerals to search for the presence of quasicrystals. They would ask for samples of the possible candidates, so they could analyze them in more detail, but unfortunately not all were available, so they made an appeal in their paper to people who possessed these samples to make them available.

For a few years nothing happened. Then they were contacted by a curator of the Museum of Natural History in Florence, Italy, who had a sample called Khatyrkite, which had been found in 1978 in extreme northeastern Siberia. This sample, a complex mixture of aluminum-containing minerals, also comprised a quasicrystalline area, the first natural quasicrystal ever found, of composition Al63Cu24Fe13, similar to a known stable artificial quasicrystal.

Understanding more about this sample required finding out precisely where it was found in the first place, and at this point the scientists had to work like Da Vinci code characters, reconstructing the path of the sample through the notes of a dead private collector in Amsterdam, to a smuggler in Romania, then on to a museum in St. Petersburg and finally to the banks of the Kathyrkha river in northeast Siberia, and getting in touch with the person who physically found the mineral. They are now thinking of organizing an expedition to find out whether there are more quasicrystals in the area.


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