STRUCTURAL, ELASTIC AND ELECTRONIC PROPERTIES OF OXYGEN SUBSTITUTION IN CUBIC Zr3N4 AND Ti3N4

Abstract

The structural, elastic and electronic properties of O-doped and un-doped cubic Zr 3 N 4 and Ti 3 N 4 are studied by first principles calculations based on the density functional theory. The bulk and shear moduli, as well as Young's moduli, decrease after doping with oxygen, which is due to the lengthening of the metal-nitrogen bond as well as the inflation of the cell volume. The changes in elastic properties are consistent with available experimental results. Both nitrides change from brittle to ductile when doped with oxygen, and all materials can be regarded as being elastic isotropic. The band structure and density of states are calculated to discuss the electronic properties of O-doped cubic Zr 3 N 4 and Ti 3 N 4, the presence of oxygen has significant influence on the electronic structure near the Fermi level. The gap at Fermi level is vanished which confirms the metallic character when O is introduced into nitrides. It means that doping with oxygen will have important effects on the optical properties of Zr and Ti nitrides.