First principles study on structural and electronic properties and defect formation enthalpies of cubic Hf3N4 under high pressure

Abstract

Using the self-consistent density functional method, we investigate the structural and electronic properties of cubic Hf3N4 with Th3P4 structure at ambient and high pressures. The lattice parameters, cell volume, bulk modulus, and pressure derivative at ambient pressure are obtained, which are in excellent agreement with the available measurements. The change of bond lengths for two different types of Hf–N bond with pressure suggests that the tetrahedral Hf–N bond is slightly less compressible than the octahedral ones, which agree well with the Zr3N4 and Zn3N2 results. The band gap pressure coefficient for c-Hf3N4 are fitted, which are 8.5 × 10−2 eV/GPa and –7.0 × 10−5 eV/(GPa)2, respectively. Based on the density of states analysis, band structure suggests that the investigated material can be used as a semiconductor optical material. Mulliken population analysis shows that the charge density of the Hf atom is less sensitive to pressure variation than that of the N atom. At last, the defect formation enthalpies of the cubic Hf3N4 are calculated.