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Zheng Y, Hoffman A, Huang K. Nitridation of diamond(111) surface by density functional theory. J Chem Phys 2024; 160:214713. [PMID: 38842494 DOI: 10.1063/5.0196681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 05/23/2024] [Indexed: 06/07/2024] Open
Abstract
Density functional theory was employed to examine the adsorption and thermal evolution of nitrogen species on diamond(111) impacted by microwave N2 plasma. On bare domains of diamond, as represented by the models of C(111)-2 × 1 and graphite-like C(111), N2(ad) is identified as the major surface species; the desorption of N2(ad) proceeds on both models via a concerted process of breaking two C-N bonds. By contrast, there is evidence of the formation of (NH)2(ad) via the insertion reaction of microwave N2 plasma on hydrogenated domains of diamond, as represented by the models of C(111)-2 × 1-H and C(111)-1 × 1-H. Interestingly, contrasting dynamics of desorption of (NH)2(ad) are presented on these two models, that is, via sequential breaking of two C-N bonds on C(111)-2 × 1-H and via concerted breaking of both C-N bonds on C(111)-1 × 1-H. Our results demonstrate that the observed diversity of surface nitrogen species in composition, bonding, vibration, and desorption in prior experiments is linked to domains of a variety of surface terminations and reconstructions on diamond(111).
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Affiliation(s)
- Yusen Zheng
- Chemistry Program, Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong Province 515063, China
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Alon Hoffman
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Kai Huang
- Chemistry Program, Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong Province 515063, China
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Peeters S, Kuwahara T, Härtwig F, Makowski S, Weihnacht V, Lasagni AF, Dienwiebel M, Moseler M, Moras G. Surface Depassivation via B-O Dative Bonds Affects the Friction Performance of B-Doped Carbon Coatings. ACS APPLIED MATERIALS & INTERFACES 2024; 16:18112-18123. [PMID: 38547870 PMCID: PMC11011640 DOI: 10.1021/acsami.3c18803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/27/2024] [Accepted: 03/04/2024] [Indexed: 04/12/2024]
Abstract
Boron doping of diamond-like carbon coatings has multiple effects on their tribological properties. While boron typically reduces wear in cutting applications, some B-doped coatings show poor tribological performance compared with undoped films. This is the case of the tribological tests presented in this work in which an alumina ball is placed in frictional contact with different undoped and B-doped amorphous carbon coatings in humid air. With B-doped coatings, a higher friction coefficient at a steady state with respect to their undoped counterparts was observed. Estimates of the average contact shear stress based on experimental friction coefficients, surface topographies, and Persson's contact theory suggest that the increased friction is compatible with the formation of a sparse network of interfacial ether bonds leading to a mild cold-welding friction regime, as documented in the literature. Tight binding and density functional theory simulations were performed to investigate the chemical effect of B-doping on the interfacial properties of the carbon coatings. The results reveal that OH groups that normally passivate carbon surfaces in humid environments can be activated by boron and form B-O dative bonds across the tribological interfaces, leading to a mild cold-welding friction regime. Simulations performed on different tribological pairs suggest that this mechanism could be valid for B-doped carbon surfaces in contact with a variety of materials. In general, this study highlights the impact that subtle modifications in surface and interface chemistry caused by the presence of impurities can have on macroscopic properties, such as friction and wear.
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Affiliation(s)
- Stefan Peeters
- Fraunhofer
IWM, MiktroTribologie Centrum μTC, Wöhlerstraße 11, 79108 Freiburg, Germany
| | - Takuya Kuwahara
- Fraunhofer
IWM, MiktroTribologie Centrum μTC, Wöhlerstraße 11, 79108 Freiburg, Germany
- Osaka
Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, 558-8585 Osaka, Japan
| | - Fabian Härtwig
- Fraunhofer
IWS, Winterbergstraße 28, 01277 Dresden, Germany
- Technische
Universität Dresden, Institut für
Fertigungstechnik, George-Bähr-Straße
3c, 01069 Dresden, Germany
| | | | | | - Andrés Fabián Lasagni
- Fraunhofer
IWS, Winterbergstraße 28, 01277 Dresden, Germany
- Technische
Universität Dresden, Institut für
Fertigungstechnik, George-Bähr-Straße
3c, 01069 Dresden, Germany
| | - Martin Dienwiebel
- Fraunhofer
IWM, MiktroTribologie Centrum μTC, Wöhlerstraße 11, 79108 Freiburg, Germany
- Karlsruhe
Institute of Technology (KIT), IAM – Institute for Applied
Materials, Straße am Forum 7, 76131 Karlsruhe, Germany
| | - Michael Moseler
- Fraunhofer
IWM, MiktroTribologie Centrum μTC, Wöhlerstraße 11, 79108 Freiburg, Germany
- University
of Freiburg, Institute of Physics, Herrmann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Gianpietro Moras
- Fraunhofer
IWM, MiktroTribologie Centrum μTC, Wöhlerstraße 11, 79108 Freiburg, Germany
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