Department of Materials Science and Engineering

Research from the Hennig Group:

Figure 1 & 2: Structure search methods discovered high-pressure LiBe compounds that exhibit remarkable quasi-2D electronic properties within a 3D crystal structure.  The large size differences between the ionic cores of Li and Be result in charge transfer from the Li cores into layers characterized by delocalized states in the vicinity of Be.

Even though the lightest known metals, lithium (Li) and beryllium (Be), do not bind to one another under normal atmospheric or ambient pressure, our interdisciplinary research predicts that Li and Be will bond under higher levels of pressure and form stable Li-Be alloys that may be capable of superconductivity. Superconductivity is the flow of electricity with zero resistance. Little work has been carried out to predict the properties of metals under high pressure and this work aims to unite the efforts of theorists and experimentalists.

Four stable Li-Be alloys have been predicted by the computational study, the alloy with the ration of one Li atom to one Be atom (LiBe) shows the greatest potential for superconducting applications. The most unexpected finding in the study is the prediction of two-dimensional electron gas layers within a tightly compressed three-dimensional LiBe compound. When layers of Li and Be are squeezed together at elevated pressures, ranging from five to ten times greater than the pressure at which diamond forms, outer electrons from the Li layer get squeezed into the vicinity of the Be layer, forming two-dimensional gas layers. It is still unknown whether these theoretical Li-Be alloys will become notable superconductors, but creating and testing these compounds will be relatively simple.