Phase transition and elastic properties of TiN under pressure from first-principles calculations

The structural phase transition and elastic properties of Titanium Nitride (TiN) are investigated using density functional theory (DFT) method within the Perdew-Burke-Ernzerhof (PBE) form of generalized gradient approximation (GGA). Our theoretical equilibrium structural parameters of TiN are in good agreement with the available experimental results and other theoretical values. The predicted phase transition from NaCl-type (B1) to CsCI-type (B2) structure occurs at ca. 341.9 GPa. This conclusion is in agreement with that of Ahuja et al., contrary to the calculation of Ojha et al. using a two-body interionic potential theory. In addition, it is found that the zinc-blende type (B3) and WC structures are not stable in the whole pressure range considered. Especially, the elastic properties of BI and B2 structures for TiN under pressures are studied for the first time. The bulk moduli, shear moduli, compressional and shear wave velocities of B1-TiN and B2-TiN are obtained successfully and these results increase monotonically with increasing pressure. By analyzing of BIG, the brittle-ductile behavior of TiN is assessed. In addition, polycrystalline elastic properties are also obtained successfully for a complete description of elastic properties. (C) 2014 Elsevier B.V. All rights reserved.