物理学报2025，Vol.74Issue(7)：248-259,12.DOI:10.7498/aps.74.20241665
层状氮化物BaMN2(M=Ti,Zr,Hf)各向异性物理性质的第一性原理研究
First-principles study of anisotropic physical properties of layered nitride BaMN2(M=Ti,Zr,Hf)
摘要
Abstract
Ternary layered nitrides have received widespread attention due to their unique electrical,optical and optoelectronic properties,which are promising for the fabrication of low-cost and high-efficiency optoelectronic materials,solar cell materials and photocatalysts.Although there is a lack of experimental reports on BaTiN2 so far,BaZrN2 and BaHfN2 have been synthesized experimentally by solid state methods.However,their optical and electrical transport properties have not been investigated systematically.This work is to systematically investigates the mechanical,electronic,optical absorption,carrier transport,and dielectric response properties of Ba MN2(M=Ti,Zr,Hf)nitrides through first-principles calculations based on density functional theory.Due to the quasi-two-dimensional layered arrangement of[MN2]2-slabs,the ionic bonds between Ba2+and N3-,and the weak interactions between the slabs,the deformation along this direction is most likely to occur under the action of external stress.BaMN2 nitrides exhibit significant anisotropic physical properties.Firstly,the mechanical properties of BaMN2,such as bulk modulus,shear modulus,Young's modulus,and Poisson's ratio,show prominent anisotropy.The lower modulus,higher Poisson's ratios and Pugh's modulus ratios indicate good flexibility of the BaMN2 nitrides.In addition,BaMN2 has indirect bandgap values(1.75-2.25 eV)within the visible-light energy range,which meets the basic requirement for the band gap of a photocatalyst for water splitting(greater than 1.23 eV).Moreover,BaMN2 has suitable band-edge positions.The appropriate bandgap values and band-edge positions indicate their broad application prospects in the absorber layer of solar cells and photocatalytic water decomposition.Due to the significant difference in the effective mass of its charge carriers between different directions,BaMN2 exhibits ultrahigh anisotropic carrier mobility(on the order of 103 cm2·s-1·v-1)and lower exciton binding energy.At the same time,there are significant differences in atomic arrangement and bonding interactions between the in-plane direction and out of plane direction,resulting in high anisotropic visible-light absorption coefficient(on the order of 105 cm-1)in the low energy region.In contrast,the increase of the opportunity for electrons to transition from occupied to unoccupied states leads to more complex light absorption and relatively reduced anisotropy in higher energy region.Furthermore,the special layered structure has lower polarizability and higher vibration frequency along the vertical direction perpendicular to the[MN2]2 layers,rendering BaMN2 nitrides show high dielectric constants.These excellent anisotropic mechanical,optoelectronic,and transport properties allow BaMN2 layered nitrides to be used as promising semiconductor materials in the fields of optoelectronics,photovoltaics,and photocatalysis.关键词
氮化物/载流子迁移率/各向异性/第一性原理研究Key words
nitrides/carrier mobility/anisotropy/first-principles study引用本文复制引用
虞健祥,梁华琳,杨轶钧,明星..层状氮化物BaMN2(M=Ti,Zr,Hf)各向异性物理性质的第一性原理研究[J].物理学报,2025,74(7):248-259,12.基金项目
国家自然科学基金(批准号:12264011)和中国大学生创新项目(批准号:202410596471)资助的课题. Project supported by the National Natural Science Foundation of China(Grant No.12264011)and the China Undergraduate Innovation Research Program(Grant No.202410596471). （批准号:12264011）
