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13. Li and Be

Hoffman, Hennig, and Ashcroft

(l. to r.) Roald Hoffmann, Richard Hennig, Neil Ashcroft

Roald Hoffmann, Chemistry and Chemical Biology, Richard G. Hennig, Materials Science and Engineering, Neil W. Ashcroft, Physics, and research colleagues used computer modeling and “chemical intuition” to discover hypothetical conditions in which lithium (Li) and beryllium (Be), when squeezed together under hundreds of thousands of atmospheres of pressure, bind to form stable—and potentially superconducting—alloys. This totally unexpected combination of two of the simplest elements would be highly complex, with layers of electrons forming quasi–two-dimensional sheets between tightly packed nuclei. Ashcroft’s research group predicted and confirmed in the 1990s that Li alone at high pressure could be a superconductor. Beryllium alone is not a superconductor, but many of the element’s characteristics indicate that it could play a role in a superconducting compound. The researchers do not yet know if the elements—which do not mix under normal circumstances—will create an exceptional superconductor when combined or if the alloys will retain their peculiar structure when returned to normal atmospheric pressures. A superconductor that requires constant squeezing to millions of atmospheres is not useful, so the researchers are now investigating new ways to exert the pressure necessary to create the alloys. This may mean looking beyond mechanical techniques to chemical elements or compounds that, when added to the mix, could serve a compressing or bonding function.

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