Study On The Physical Properties Of The Van Der Waals Layered Material YCl

Although known for their ease of exfoliation to few or monolayers,the vast majority of van der Waals(vdW)layered materials still have interlayer interactions that are difficult to ignore.In addition to vdW interactions,various cross-layer covalent-like quasi-bonds and long-range Coulomb attraction play a dominant role between material layers.The understanding and exploration of the types,strengths and generation mechanisms of interlayer interactions are still at a rather preliminary stage.On the other hand,as a new member of the family of layered materials,layered electrides are considered to have bright application prospects due to their high carrier mobility and low work function close to that of alkali metals because they contain anionized electrons distributed in lattice voids.Unfortunately,the known layered electrides are very unstable in air due to the direct exposure of the active anionic electrons on the surface of the molecular layer.Here,based on first-principles calculations,we explore a novel vdW layered electride YCl with anionic electron distribution within the layers.We predict that the monolayer of YCl can not only exist stably,but also has strong thermal stability and excellent in-plane mechanical properties,with the ability to form films independently without a substrate.Due to the unique Cl-Y-Y-Cl sandwich-like monolayer structure,the YCl interlayer interactions are very weak.It has lower interlayer coupling strength,exfoliation energy,minimum interlayer sliding potential,and weak layerdependent band structure than graphene and most two-dimensional materials.More interestingly,unlike other known layered electrides,the active anionic electrons in YCl are intrinsically encapsulated within the layer by the outer inert chloride ion layer due to an outer anion-inner cation distribution.It is this intrinsic difference in structure that gives YCl a stability that is rare in layered electrides when they are exposed to air.Our study not only reveals the unique physical properties of YCl and elucidates the mechanism of its weak interlayer coupling and strong stability generation,but also provides a new idea for the next development of vdW layered electrides.