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Wednesday, September 30, 2020 – 12:00PM to 1:00PM
Professor Eva Zurek
Title: Towards Room Temperature Superconductivity in Hydride-Based Materials Under Pressure
Location: Virtual Webex Address: https://duke.zoom.us/j/9088262425
Abstract:The pressure variable opens the door towards the synthesis of materials with unique properties, e.g. superconductivity, hydrogen storage media, high-energy density and super hard materials. Under pressure elements that would not normally combine may form stable compounds or they may adopt
novel stoichiometries. As a result, we cannot use our chemical intuition developed at 1 atm to predict phases that become stable when compressed. To facilitate the prediction of the crystal structures of novel materials, without any experimental information, we have developed XtalOpt, an evolutionary algorithm for crystal structure prediction. XtalOpt has been applied to predict the structures of hydrides with unique compositions that become stable at pressures attainable in diamond anvil cells. We describe recent results on the binary hydrides of strontium and calcium, as well as a YH9 phase - for which a Tc of 256 K at 177 GPA has been measured. In the ternary hydride systems two different classes of superconductors are discovered - intercalated H3S perovskites, and phases containing SH honeycomb sheets. Finally, we predict a superconducting RbB3Si3 phase in the bipartite sodalite structure that could be synthesized at mild pressures and quenched to 1 atm.