Formation of 2D transition metal dichalcogenides on TiC1−xAx surfaces (A = S, Se, Te): A theoretical study

Kádas, Krisztina; Sundberg, Jill; Jansson, Ulf; Eriksson, Olle

doi:10.1557/jmr.2013.350

Cited by 2 publications

(1 citation statement)

References 45 publications

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“…The exchange-correlation energy was calculated using the generalized gradient approximation with the Perdew, Burke and Ernzerhof functional [25], including the valence states 5d 4 6s 2 for W, 3s 2 3p 4 for S and 2s 2 2p 3 for N. This scheme is known to accurately describe the physical properties of transition metal carbides and nitrides [26][27][28][29][30]. The amorphous structures were generated by means of ab initio molecular dynamics using canonical (NVT) ensembles applying the VASP package.…”

Section: Computational Detailsmentioning

confidence: 99%

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

et al. 2015

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Amorphous W-S-N in the form of thin films has been identified experimentally as an ultra-low friction material, enabling easy sliding by the formation of a WS 2 tribofilm. However, the atomic-level structure and bonding arrangements in amorphous W-S-N, which give such optimum conditions for WS 2 formation and ultra-low friction, are not known. In this study, amorphous thin films with up to 37 at.% N are deposited, and experimental as well as state-of-the-art ab initio techniques are employed to reveal the complex structure of W-S-N at the atomic level. Excellent agreement between experimental and calculated coordination numbers and bond distances is demonstrated. Furthermore, the simulated structures are found to contain N bonded in molecular form, i.e. N 2 , which is experimentally confirmed by near edge X-ray absorption fine structure and X-ray photoelectron spectroscopy analysis. Such N 2 units are located in cages in the material, where they are coordinated mainly by S atoms. Thus this ultra-low friction material is shown to be a complex amorphous network of W, S and N atoms, with easy access to W and S for continuous formation of WS 2 in the contact region, and with the possibility of swift removal of excess nitrogen present as N 2 molecules.

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Section: Computational Detailsmentioning

confidence: 99%

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

et al. 2015

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Experimental and ab initio study of the influence of a compound modifier on carbidic ductile iron

Yang

Lin

et al. 2019

Metall. Res. Technol.

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To improve the morphology of carbides in carbidic ductile iron, a compound modifier consisting of 0.1% Nb + 0.1% Ti + 0.1 wt.% Y was added to the base ductile iron with chemical composition of 3.72% C, 2.77% Si, 0.51% Mn, 0.99% Cr and balance Fe (wt.%). The effect of this compound modifier on the microstructures of carbidic ductile iron was studied. Also, first-principles calculations were carried out to better understand the modification mechanisms. The results showed that the maximum diameter of spheroidal graphite nodules decreased from 58 to 34 µm after the addition of compound modifier, and continuous carbide networks changed into a broken network. The roundness of graphite nodules decreased slightly, and the percent nodularity of the graphite nodules and the number of carbides decreased by 3 and 1.8%, respectively. Compounds with higher melting point are formed thanks to the compound modifier which acts as heterogeneous core, and the remaining Ti and Nb elements can be selectively attracted by (010) surface of Fe8Cr4C4. Furthermore, Cr elements can be easily replaced by Ti and Nb in the carbides to form more stable Fe8Cr3TiC4 and Fe8Cr3NbC4, which can prevent the continuing growth of carbide on the Fe8Cr4C4 (010) crystal surface and break the continuous network M3C. Y atoms cannot be directly adsorbed onto Fe8Cr4C4 (010) surfaces. They combine first with oxygen in the ductile iron to form Y2O3. The work of adhesion of the interface between a Y2O3 (100) and a Fe8Cr4C3 (010) is predicted to be 0.3 J/m2. The addition of Y element is found to have a positive effect on breaking up the continuity of the carbide network.

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Formation of 2D transition metal dichalcogenides on TiC_1−xA_x surfaces (A = S, Se, Te): A theoretical study

Cited by 2 publications

References 45 publications

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

Experimental and ab initio study of the influence of a compound modifier on carbidic ductile iron

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