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Accurate Mechanical and Electronic Properties of Spinel Nitrides from Density Functional Theory

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journal contribution
posted on 14.04.2021, 14:36 by Hang Hu, Gilles H. Peslherbe
The mechanical and electronic properties of both Group 14 nitrides (Si3N4, Ge3N4, and Sn3N4) and metal nitrides (Ti3N4 and Zr3N4) have been investigated with density functional theory (DFT). All nitrides feature large bulk moduli, exceeding 200 GPa, inversely proportional to the average cation–nitrogen bond length. The nitride valence band primarily involves overlap of nitrogen p-orbitals with the cation p-orbitals and metal d-orbitals for Group 14 and metal nitrides, respectively. The metal d-orbitals which essentially make up the metal nitride conduction band are accessible at a much lower energy relative to their s-p-d-hybridized Group 14 counterparts, which causes metal nitrides to have smaller band gaps than Group 14 nitrides. DFT-1/2 is shown to efficiently and properly correct the notorious electron self-interaction error associated with conventional DFT, consistently reproducing experimental band gaps within 0.1 eV. This comprehensive investigation sheds light on the similarities and differences between Group 14 and metal nitrides.