Studying The Property Of ZrN₂,HfN₂ And BC₆N's High Pressure With First-Principles

With the emerging situation of modern industrial production,the supply of various materials is increasing,and the conditions for the application of super-hard materials are becoming stricter.Looking for potential super-hard materials with high stability,high hardness and strong corrosion resistance has become a hotspot of scientific research.At present,researchers mainly use transition metals to form compounds with B,C,and N and covalent compounds with B,C,N,and O to explore super-hard materials that can break the limitations of diamond and cubic boron nitride.This paper studies the structure and physical properties of ZrN₂,HfN₂ and BC₆ N under high pressure based on the first principles of density functional theory,which provides a theoretical basis for exploring super-hard materials.In this paper,the crystal structure,elastic properties,anisotropy and electronic properties of ZrN₂ at 0 GPa to 100 GPa are firstly studied.Within the studied pressure range,ZrN₂ meets the mechanical stability and exhibits good ductility and plasticity.At 100 GPa,the bulk modulus of the material is 662 GPa,the shear modulus is 213 GPa,and the Young's modulus is 578 GPa,which indirectly predicts that ZrN₂ is a super-hard material under high pressure.In addition,the calculated anisotropy factor shows that ZrN₂ exhibits anisotropy in the studied pressure range and has good metallicity.Next,in this paper,the crystal structure,elastic constant,anisotropy factor,state density diagram of HfN₂ at 0 to 100 GPa are studied.Studies have shown that HfN₂ meets the standard of mechanical stability in the pressure range.B/G and Poisson ratio confirmed that the material has good ductility and plasticity.At 100 GPa,the bulk elastic modulus of HfN₂ is 752 GPa,the shear modulus is 347 GPa,and the Young's modulus is 902 GPa.The study found that the crystal is a super-hard material under high pressure.By studying the anisotropy factor,it is shown that Hf N₂ is anisotropic within the specified pressure range,and the density diagram of states indicates that it is metallic.At last,the physical properties of o-BC₆ N phase in C2221-B3N5,in which C atom replaces part of B atom and N atom,are studied in the range of 0 to 50 GPa.The study of crystal structure and elastic constant shows that o-BC₆ N is mechanically stable within the specified pressure range.The calculation of B/G and Poisson ratio shows that the crystal has good ductility,and the bonding force between atoms under high pressure is the central force.At 50 GPa,the bulk modulus is 497 GPa,the shear modulus is 175 GPa,and the Young's modulus is 469 GPa.The anisotropy factor indicates that it is anisotropic within 50 GPa,and the band diagram and density of states show its metallicity.In conclusion,it can be concluded that ZrN₂?HfN₂ and o-BC₆ N are super-hard materials under high pressure.