Designing highly incompressible transition metal nitrides: A new class of W0.5Al0.5N phases.

Herein, we used first-principles calculations and the particle swarm optimization technique to predict a highly incompressible W0.5Al0.5N phase with the space group R 3 ¯ m (166). Our results reveal that this phase, which was characterized by a negative formation enthalpy, is thermodynamically and dynamically stable, as revealed by the absence of imaginary modes in the phonon spectra. Furthermore, its energetic stability at a pressure of 15 GPa indicates a feasible strategy for experimental synthesis. The high performance stems from the optimized octahedral coordination between N and W/Al. Additionally, the good elastic parameters with BH of 310 GPa, GH of 206 GPa, and HV of 27 GPa confirm that it has preferable mechanical behaviors among the various W0.5Al0.5N phases and is even superior to those of the experimentally well-established NaCl-type phase. Based on the recently developed strain–stress method, it is shown that the ideal indentation strength of R 3 ¯ m (166) is about 32.7 GPa in the (1 1 ¯ 0) [0 0 1] direction, which is in excellent agreement with estimated HV. Therefore, our findings open the possibility for producing a new class of transition metal aluminum nitrides that have a broad range of applications. [ABSTRACT FROM AUTHOR]