Cubic Hf3N4 and Zr3N4: A class of hard materials

We report ab initio computer modeling of the high-pressure cubic forms of Zr3N4 and Hf3N4. 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 Hf3N4 should have a Vickers hardness similar to that of Si3N4.