Structure And Optical Properties Of Two-dimensional Van Der Waals Ba₄Al₅ And Ba₂Ni₃

Two-dimensional van der Waals materials with layered structures have become a research hotspot in recent years due to their structural characteristics and interlayer van der Waals forces,which are easy to peel off and assemble.They have broad application prospects in fields ranging from nanoelectronics to aerospace devices.Among these materials,there is a class of materials called electrides,in which electrons occupy the interstitial positions of the lattice as anions and form compounds together with cations.This type of material not only has layered structure and easy peeling properties,but also has high conductivity,high mobility,low work function and other characteristics.It is a new type of functional material with important research value.Due to its unique crystal structure characteristics,there are still relatively few reported electrides with layered structures,and research on their physical properties is still in the preliminary stage.In this paper,the electronic structure and photoelectric properties of Ba4Al5 and Ba2Ni3,two electrides with two-dimensional layered van der Waals structure,are mainly studied,which lays a foundation for their application in photoelectric devices.The main content of this paper is as follows:Based on the first principle calculation,the electronic structure characteristics of the electrides Ba4Al5 bulk and single layer with layered structure were studied.Research has shown that anionic electrons are limited in the interlayer region,and the interlayer dissociation energy of the material is about 0.77 J/m2,making it easy to mechanically peel off.Meanwhile,the calculation of the work function found that Ba4Al5 has a low work function of approximately 2.21 eV on the(001)surface,lower than the 2.6 eV of Ca2N.In addition,this paper also proves that the bulk structure of Ba4Al5 can support surface plasmon modes in the nearinfrared frequency range.The dielectric function and optical properties of the two-dimensional van der Waals material Ba2Ni3 were calculated based on first principles.The calculation results indicate that both the bulk and monolayer structures of Ba2Ni3 exhibit typical metal optical properties and have a wide light absorption coefficient.In addition,it has the characteristics of indefinite media in the low frequency range,which has important applications in metamaterial and other fields.The research in this paper enriches the two-dimensional van der Waals material family and further promotes their application research in the fields of optoelectronic devices and surface plasmons.