Cubic Hf3N4 and Zr3N4: A class of hard materials

Abstract

We report ab initio computer modeling of the high-pressure cubic forms of ${\mathrm{Zr}}_3{\mathrm{N}}_4$ and ${\mathrm{Hf}}_3{\mathrm{N}}_4.$ Equilibrium structural parameters were derived at 0 K and zero pressure for different exchange-correlation functionals. Single crystal elastic constants and bulk moduli were then computed at the athermal limit in order to quantify the stiffness of the investigated nitrides. We find that ${\mathrm{Hf}}_3{\mathrm{N}}_4$ should have a Vickers hardness similar to that of ${\mathrm{Si}}_3{\mathrm{N}}_4.$