SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Poster Session I: Nanostructures at surfaces I
O 14.6: Poster
Montag, 1. März 2021, 10:30–12:30, P
Defect-mediated ab initio thermodynamics of metastable γ-MoN(001) — •Giyeok Lee1, Hojun Lee1, Taehun Lee1,2, and Aloysius Soon1 — 1Department of Materials Science & Engineering and Center for Artificial Synesthesia Materials Discovery, Yonsei University, Seoul 03722, Republic of Korea — 2Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States
Refractory transition metal nitrides exhibit a plethora of polymorphic expressions and chemical stoichiometries. To afford a better understanding of how defects may play a role in the structural and thermodynamics of these nitrides, using density-functional theory calculations, we investigate the influence of point and pair defects in bulk metastable γ-MoN and its (001) surface. We report favorable formation of Schottky defect pairs of neighboring Mo and N vacancies in bulk γ-MoN and apply this as a defect-mediated energy correction term to the surface energy of γ-MoN(001) within the ab initio atomistic thermodynamics approach. We also inspect the structural distortions in both bulk and surfaces of γ-MoN by using the partial radial distribution function, g(r) of Mo-N bond lengths. Large atomic displacements are found in both cases, leading to a broad spread of Mo-N bond length values when compared to their idealized bulk values. We propose that these structural and thermodynamic analysis may provide some insight to a better understanding of metastable materials and their surfaces.