The nature do not stop surprising. And University of Florence geologist Luca Bindi was literally speechless to discover that lightning struck a power line in Nebraska’s Sand Hills sand dunes had created material never before identified by science. It is a ‘quasicrystal’ with a never seen composition up to now and that can revolutionize the known history of these materials. The unusual finding, carried out in collaboration with researchers from Princeton University, Caltech and the University of South Florida, has just been published in ‘PNAS’.
“Quasicrystals,” explains Bindi, “are materials in which the atoms are arranged like a mosaic, in regular patterns but never repeat themselves in the same way, unlike what happens in ordinary crystals. It was Dan Shechtman, later awarded a Nobel for his discoveries, who studied their structure in the 1980s, which also makes them valuable for applications in various industrial sectors. Fifteen years ago, it was I who discovered that this material also existed in nature, thanks to the identification of the quasicrystal in a meteorite sample preserved in the Museum of Natural History of the University of Florence. After that, we discovered other quasicrystals of an extraterrestrial nature and the first man-made quasicrystal, formed in the detonation process of the first nuclear test carried out by the US in 1945: all produced under conditions of extreme pressures and temperatures in matter of nanoseconds.
a new idea
From those previous findings, the idea arose to search, together with his American colleagues, for extraordinary materials formed in exceptional conditions. And there are few things on Earth that are more powerful and exceptional than lightning. The researchers’ attention focused on the so-called ‘fulgurites’, which are formed when the heat generated by the electrical discharge melts quartz-rich silica sand.
«The sample we analyzed -explains the researcher- was probably formed by the fusion of sand and material from a power line struck by a powerful lightning discharge. The presence of silica glass suggests that it reached temperatures of at least 1710 °C and investigations conducted at the University’s Center for Structural Crystallography confirmed that the quasicrystal has a dodecagonal symmetry prohibited by periodic crystallography and a previously undocumented composition.”
“These data -concludes Bindi-, suggest in which directions the search for other quasicrystals could go and provide more elements to develop technologies capable of synthesizing them.”
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