Point-defect engineering of MoN/TaN superlattice films: A first-principles and experimental study

0541010 - ÚFM 2021 RIV GB eng J - Journal Article
Koutná, N. - Hahn, R. - Zálešák, J. - Friák, Martin - Bartosik, M. - Keckes, J. - Šob, Mojmír - Mayrhofer, P. H. - Holec, D.
Point-defect engineering of MoN/TaN superlattice films: A first-principles and experimental study.
Materials and Design. Roč. 186, JAN (2020), č. článku 108211. ISSN 0264-1275. E-ISSN 1873-4197
R&D Projects: GA MŠMT(CZ) 8J18AT008; GA MŠMT LM2015069
Institutional support: RVO:68081723
Keywords : tribological properties * mechanical-properties * al-n * coatings * elasticity * stability * toughness * alloys * growth * Superlattices * Vacancies * Ab initio * Metastable phases * xrd * edx
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 7.991, year: 2020
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S0264127519306495?via%3Dihub

Superlattice architecture represents an effective strategy to improve performance of hard protective coatings. Our model system, MoN/TaN, combines materials well-known for their high ductility as well as a strong driving force for vacancies. In this work, we reveal and interpret peculiar structure-stability-elasticity relations for MoN/TaN combining modelling and experimental approaches. Chemistry of the most stable structural variants depending on various deposition conditions is predicted by Density Functional Theory calculations using the concept of chemical potential. Importantly, no stability region exists for the defect-free superlattice. The X-ray Diffraction and Energy-dispersive X-ray Spectroscopy experiments show that MoN/TaN superlattices consist of distorted fcc building blocks and contain non-metallic vacancies in MoN layers, which perfectly agrees with our theoretical model for these particular deposition conditions. The vibrational spectra analysis together with the close overlap between the experimental indentation modulus and the calculated Young's modulus points towards MoN0.5/TaN as the most likely chemistry of our coatings. (c) 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Permanent Link: http://hdl.handle.net/11104/0318588