First-principles study of the structural and electronic properties of the cubic Zr3 N4 under high pressure

Abstract

The structural and electronic properties of cubic zirconium nitride (c-Zr3N4) with the Th3P4 structure under high pressure were studied by the local density functional pseudopotential method. The obtained structural data at ambient pressure are in agreement with the experimental values. Analysis of the change of bond lengths of two different types of Zr–N bond with pressure suggests that the octahedral Zr–N is slightly less compressible than the tetrahedral ones. We find that c-Zr3N4 may have a very high hardness similar to that of γ-Si3N4. By fitting the calculated bandgap, the first- and second-order pressure coefficient for the direct bandgap of the c-Zr3N4 were determined to be 3.35 × 10−2 eV/GPa and −1.0 × 10−5 eV/(GPa)2, respectively. Based on the Mulliken population analysis, the c-Zr3N4 was found to have higher and higher covalent character with increasing pressure, and the charge of the N atom is more sensitive to pressure variation than that of the Zr atom.