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Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN₂ (TM?=?Ti, Zr, and Hf).

ABSTRACT: Motivated by recent successful synthesis of transition metal dinitride TiN₂, the electronic structure and mechanical properties of the discovered TiN₂ and other two family members (ZrN₂ and 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 TMN₈ units. However, as compared with traditional fcc transition metal mononitride (TMN), the TMN₂ possess a larger elastic anisotropy may impose certain limitations on possible applications. Further mechanical strength calculations show that tetragonal TMN₂ exhibits 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 TMN₂ along 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 TMN₂ at the atomic level during shear deformation can be attributed to the collapse of TMN₈ units with breaking of TM-N bonds through the bonding evolution and electronic localization analyses.

SUBMITTER: Zhang M

PROVIDER: S-EPMC5103277 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2 (TM = Ti, Zr, and Hf).

Zhang Meiguang M Cheng Ke K Yan Haiyan H Wei Qun Q Zheng Baobing B

Scientific reports 20161110

Motivated by recent successful synthesis of transition metal dinitride TiN2, the electronic structure and mechanical properties of the discovered TiN2 and other two family members (ZrN2 and 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 d ...[more]

PMID: 27830728

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Project description:High-hardness materials with ductile deformation behavior have recently piqued interest due to their prospective applications, particularly as hard and protective coatings. The crack formation, especially in metal and ceramic materials, is one of the biggest problems of the surface hard coatings on heavy-duty tools. In this regard, mechanical properties (Vickers hardness, fracture toughness, machinability index, index of brittleness, as well as Pugh's ratio) have been studied for the metallic boro-carbides of A2BC (A = Ti, Zr, Hf, and W) compounds using the state-of-the-art density functional theory in detail. The compounds under investigation are both thermodynamically and mechanically stable. The value of Vickers hardness (in GPa) for A2BC (A = Ti, Zr, Hf, and W) compounds are 28.20, 23.12, 12.44, and 35.70, respectively, which indicates the W2BC could be a member of the hard family (H v > 30 GPa). Pugh's ratio suggests ductile deformation for the W2BC compound, whereas the other three (Ti2BC, Zr2BC, and Hf2BC) compounds exhibit brittle deformation behavior. The W2BC compounds have the highest ductility among the other metallic boro-carbides (M2BC; M = V, Nb, Mo and Ta) and some other benchmark coating materials (TiN, TiAlN, C-BN, and Cr0.5Al0.5N). The fracture toughness (K IC) values are in the following sequence: Zr2BC < Ti2BC < Hf2BC < W2BC, which indicates that, the highest resistance (K IC = 4.96 MPam1/2) found for W2BC is suitable to prevent the crack propagation within the solid. In addition, the structural, electronic, optical, and thermal properties are also investigated for the A2BC (A = Ti, Zr, Hf, and W) compounds. The Ti2BC (W2BC) reflectivity spectra never fall below 53 (45)% in the 0 to 10.3 eV (0 to 16.70 eV) photon energy range, suggesting that these compounds have promise for usage as coating materials to reduce solar heating. Hf2BC and W2BC compounds could also be exploited as promising thermal barrier coating materials, while Ti2BC could be used as heat sink material based on the results of Debye temperature, melting temperature, thermal conductivity, and thermal expansion coefficient. The electronic properties reveal the metallic behavior of these compounds. The results obtained here are compared with those of some commercially known compounds, where available.

Dataset Information

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN₂ (TM?=?Ti, Zr, and Hf).

Publications

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN<sub>2</sub> (TM = Ti, Zr, and Hf).

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Dataset Information

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2 (TM?=?Ti, Zr, and Hf).

Publications

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN<sub>2</sub> (TM = Ti, Zr, and Hf).

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN₂ (TM?=?Ti, Zr, and Hf).