Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2(TM = Ti, Zr, and Hf).
Motivated by recent successful synthesis of transition metal dinitride TiN2, the electronic structure and mechanical properties of the discovered TiN2and other two family members (ZrN2and HfN2) have been thus fully investigated by using first-principles calculations to explore the possibilities and provide guidance for future experimental efforts. The incompressible nature of these tetragonal TMN2(TM = Ti, Zr, and Hf) compounds has been demonstrated by the calculated elastic moduli, originating from the strong N-N covalent bonds that connect the TMN8units. However, as compared with traditional fcc transition metal mononitride (TMN), the TMN2possess a larger elastic anisotropy may impose certain limitations on possible applications. Further mechanical strength calculations show that tetragonal TMN2exhibits a strong resistance against (100)[010] shear deformation prevents the indenter from making a deep imprint, whereas the peak stress values (below 12 GPa) of TMN2along shear directions are much lower than those of TMN, showing their lower shear resistances than these known hard wear-resistant materials. The shear deformation of TMN2at the atomic level during shear deformation can be attributed to the collapse of TMN8units with breaking of TM-N bonds through the bonding evolution and electronic localization analyses.
College of Physics and Optoelectronic Technology, Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721016, China.
Meiguang
M
Zhang
College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225, China.
Ke
K
Cheng
College of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji 721013, China.
Haiyan
H
Yan
School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China.
Qun
Q
Wei
College of Physics and Optoelectronic Technology, Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721016, China.
Baobing
B
Zheng