Effect of Ti doping on mechanical and optical properties of super-hard I2d-CN2 materials

Abstract

The effect of Ti doping on the mechanical and optical properties of superhard materials I2d-CN₂ are investigated based on density functional theory calculations. Both the Ti doping ways and concentrations used for substituting the C or N atoms are considered. The dynamic stability of each structure is examined by the molecular dynamics simulations. The carrier mobility and relaxation time, optical absorption, photoconductivity, elastic modulus and Vickers hardness are calculated using fully optimized structures. The results show that the energy band gaps of the doped structures are narrowed, while the absorption coefficient and photoconductivity are significantly enhanced in the visible light for the larger doping concentrations. However, the elastic modulus and Vickers hardness demonstrate that the Ti-doped I2d-CN₂ materials are still very hard. Finally, the preferable Ti-doping way and concentration for the moderate optical and mechanical properties are proposed.