Issue 17, 2015

Phase stability, chemical bonding and mechanical properties of titanium nitrides: a first-principles study

Abstract

We have performed first-principles evolutionary searches for stable Ti–N compounds and have found, in addition to the well-known rock-salt TiN, new ground states Ti3N2, Ti4N3, Ti6N5 at atmospheric pressure, and Ti2N and TiN2 at higher pressures. The latter nitrogen-rich structure contains encapsulated N2 dumbbells with a N–N distance of 1.348 Å at 60 GPa. TiN2 is predicted to be mechanically stable and quenchable. Our calculations on the mechanical properties (bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and hardness) are in excellent agreement with the available experimental data. Further analyses of the electronic density of states, crystal orbital Hamilton population and the electron localization function reveal that the hardness is enhanced by strengthening directional covalent bonds and disappearance of Ti–Ti metallic bonding.

Graphical abstract: Phase stability, chemical bonding and mechanical properties of titanium nitrides: a first-principles study

Supplementary files

Article information

Article type
Paper
Submitted
11 Jan 2015
Accepted
26 Mar 2015
First published
01 Apr 2015

Phys. Chem. Chem. Phys., 2015,17, 11763-11769

Author version available

Phase stability, chemical bonding and mechanical properties of titanium nitrides: a first-principles study

S. Yu, Q. Zeng, A. R. Oganov, G. Frapper and L. Zhang, Phys. Chem. Chem. Phys., 2015, 17, 11763 DOI: 10.1039/C5CP00156K

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