Stable Structures and Superconductivity in a Y-Si System under High Pressure.

Recently, the discovery of superconductivity in compressed electrides offers a promising route toward searching for high superconductivity in a high-pressure community. However, only a few superconducting electrides have been successfully found thus far, thereby limiting the variety of superconducting electride examples. In this work, we performed extensive structure searches on a high-pressure Y-Si system by using CALYPSO structure prediction methodology. Our simulations identified several stable stoichiometries of YSi, YSi2, YSi3, Y5Si3, Y2Si, and Y3Si under high pressure. These structures contain a diversity of structure configurations, including silicon chains, Si3 trilaterals, Si4 quadrilaterals, Si6 hexagons, Si8 rings, a Si4-Si6-Si8 frame, as well as a silicon layer. Remarkably, Y3Si is predicted to be an electride with a superconducting critical temperature (Tc) of ∼11.2 and 14.5 K at 30 and 50 GPa, respectively. These results highlight the role of the electrons at the Fermi surface in determining the superconductivity of predicted structures.