The Investigation On Titanium Nitrogen Compounds Based On The First Principles

In recent years,first-principles calculations have gradually become a common method for the theoretical analysis of material properties and have played a significant role in scientific research.CASTEP,as a first-principles quantum mechanics code for performing electronic structure calculations,can be used to simulate various materials including crystal ine solids,molecules,and amorphous materials within the framework of density functional theory.In order to obtain the theoretical basis for their application,we used CASTEP program to theoretically calculate Ti-N compounds in this paper.As a new type of ceramic material,TiN?titanium nitride?plays an important role in high-strength,high-hardness,high-temperature resistance etc.,both as a reflective material in the manufacturing industry and as a diffusion barrier in the microelectronics industry.However,it is not uncommon to study its isomeric structure at domestic and foreign.In particular,it is widely discussed that phase transitions under high pressure are relatively extensive.However,studies on the elastic properties of TiN isomers,especially optical properties,are relatively rare.In addition,in order to find the toughness of TiN and the hardness of TiC,the research on the solid solution between them has gradually become a research hotspot.However,there are few international studies on the electronic structure,mechanical properties,elastic properties and optical properties of TiN_1-xC_x?x=0,0.25,0.5,0.75,1?ternary compounds.In this paper,we use material analysis software to model typical materials and do geometry optimization of titanium nitride?TiN?including its B1?NaCl type?,B2?CsCl type?,B3?sphalerite type?,and Bh?WC type?structure.By using the first-principles calculations based on density functional theory,the total state density and partial state density of these materials are obtained to study the electronic structure properties of the material,and its elastic constants and elastic moduli are calculated to discuss its elastic properties as well as covalent interactions and thermodynamic properties.In addition,the dielectric function etc.parameters of titanium-nitride compounds are also calculated in this paper,which provides a theoretical basis for studying the optical properties of titanium nitride.In this paper,we replace the N atoms in the B1 structure of TiN with C atoms to construct the unit cell structure of TiN_1-x-x C_x?x=0.25,0.5,0.75?.It performs geometric optimization and property calculations.By analyzing the band structure and density of states,all of the objects in this study are metallic.The TiN of B2 and B3 exhibited ductility,and other compounds belonged to brittle compounds.The TiN_1-xC_x has elastic anisotropy and the TiN anisotropy is the largest,while the TiN anisotropy of the B2 phase is the largest among the four isomers of TiN.In addition,the Debye temperature and lattice thermal conductivity of titanium-nitrogen compounds are also calculated.Furthermore,the optical properties of TiN_1-xC_x ternarycompoundsincludingabsorption,reflectivity,refractiveindex,and photoconductivity with photon energy under different compositions are also given in this paper.This article compares the current theoretical results with existing experimental or theoretical results,and shows the accuracy and reliability of the theoretical results presented in this paper.