The tribological behavior of type II textured MX2 (M=Mo, W; X=S, Se) films

Cohen, Sidney R.; Rapoport, L.; Ponomarev, E. A.; Cohen, Hagai; Tsirlina, T.; Tenne, Reshef; Lévy‐Clément, C.

doi:10.1016/s0040-6090(97)01218-2

Cited by 64 publications

(38 citation statements)

References 16 publications

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“…As aplicações do dissulfeto de molibdênio vão desde baterias no estado sólido que utilizam meio não aquoso e íons lítio intercaláveis [9][10][11] , células solares 12 , como lubrificantes sólidos 13 , catalisadores [14][15][16][17][18] , onde desempenha um papel de importância fundamental, além de outras.…”

Section: Figura 1 Representação Esquemática Das Estrutura Das Fases unclassified

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Dissulfeto de molibdênio, um material multifuncional e surpreendente

Wypych

2002

Quím. Nova

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Recebido em 6/10/00; aceito em 4/4/01 MOLYBDENUM DISULFIDE, A MULTIFUNCTIONAL AND REMARKABLE MATERIAL. The aim of this work is to review the chemical and physical properties of layered molybdenum disulfide. The three polymorphic/polytypic modifications of the compound were found, the polytypes 2H (molybdenite) and 3R are semiconductors while the polymorph 1T is an electronic conductor. 2H-MoS 2 has several important industrial applications as hydrotreatment catalysts, energy storage devices, solar cells, solid lubricants, among others. When intercalated, the 2H phase changes to a distorted 1T phase, producing unstable intercalation compounds that can be exfoliated in solution, producing single layers and consequently nanocomposites. The direct synthesis of the 1T phase produces stable intercalation compounds. Recently molybdenum disulfide was prepared as nanotubes and fulerenelike structures that bring new insights in the investigation of this important material.Keywords: molybdenum disulfide; intercalation; layered materials. INTRODUÇÃOO dissulfeto de molibdênio pertence a uma classe de materiais conhecidos como compostos lamelares e ocorre em três modificações polimórficas/politípicas 1,2 . A fase mais comum (2H) ocorre na natureza na forma de molibdenita. Nas modificações 2H e 3R, áto-mos de molibdênio estão ligados covalentemente à átomos de enxofre numa geometria trigonal prismática regular (Figura 1). Os prismas trigonais estão ligados entre si pelas arestas, produzindo unidades bidimensionais conhecidas como lamelas. Essas lamelas que, estão conectadas por forças fracas do tipo Van der Waals, podem se ordenar de maneira diferente originando os dois politipos. Na fase 1T a forma ondulada se deve à distorção da esfera de coordenação octaédrica do centro metálico 2 . A forma do politipo 1T não distorcida está representada na Figura 1. Figura 1. Representação esquemática das estrutura das fases 2H, 3R e 1T (não distorcida), do dissulfeto de molibdênio.As propriedades dos politipos são diferentes. A fase 1T é condutora 2 enquanto que as fases 2H e 3R são diamagnéticas e semicondutoras 3. Além das três formas conhecidas de hábito cristalino, o dissulfeto de molibdênio se apresenta na forma amorfa 4,5 , como nanotubos 6,7 e esferas de dimensões nanoscópicas 7,8 semelhantes as estruturas dos fulerenos.As aplicações do dissulfeto de molibdênio vão desde baterias no estado sólido que utilizam meio não aquoso e íons lítio intercaláveis [9][10][11] , células solares 12 , como lubrificantes sólidos 13 , catalisadores [14][15][16][17][18] , onde desempenha um papel de importância fundamental, além de outras.Um dos processos de síntese do dissulfeto de molibdênio nas fases polimórficas 2H e 3R é a reação térmica direta entre o molibdênio metálico e enxofre elementar em ampolas de quartzo. Quando cristais grandes forem necessários utiliza-se o método de transporte de vapor químico com um halogeneto como o iodo como agente transportante 19 (Eq.1).Mo + 2 S ® MoS 2 + 2 I 2 « MoI 4 + S 2Nesse procedimento, quantidades estequ...

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Section: Figura 1 Representação Esquemática Das Estrutura Das Fases unclassified

“…Esses materiais atuam em condições extremas de aqueci-mento ou resfriamento, onde lubrificantes líquidos comuns não seriam adequados 13,38 . Existe um grande potencial na utilização de materiais intercalados com cátions volumosos devido a possibilidade do controle da interação interlamelar.…”

Section: Uso Em Lubrificantes Sólidosunclassified

Dissulfeto de molibdênio, um material multifuncional e surpreendente

Wypych

2002

Quím. Nova

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“…Among them, the MoS 2 is well-known as a conventional lubricant [5] and catalyst for hydrogen evolution [6,7]. Recent investigations of the materials showed that mono-and few-layered MoS 2 are also advanced in high efficient transistors [8,9], photoelectronics [10], and electrocatalysis [11].…”

Section: Introductionmentioning

confidence: 99%

Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS₂

Pankratov

Hoszowska

Dousse

et al. 2015

J. Phys.: Condens. Matter

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We report on vacuum ultraviolet (VUV) excited photoluminescence (PL) spectra emitted from a chemical vapor deposited MoS 2 few-layered film. The excitation spectrum was recorded by monitoring intensities of PL spectra at ~1.9 eV. A strong wide excitation band peaking at 7 eV was found in the excitation. The PL excitation band is most intensive at liquid helium temperature and completely quenched at 100 K. Through first-principles calculations of photoabsorption in MoS 2 , the excitation was explicated and attributed to transitions of electrons from p-and d-type states in the valence band to the d-and p-type states in the conduction band. The obtained photon-in/photon-out results clarify the excitation and emission behavior of the low dimensional MoS 2 when interacting with the VUV light sources.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] This important characteristic has its origin in their nanoscopic anisotropic crystal structure consisting of strong covalent intra-layer bonding and weaker dispersive interlayer interactions. 15 One important consequence of this unique structure is the fact that the layers may slide on top of each other while overcoming relatively small energetic barriers.…”

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Interlayer commensurability and superlubricity in rigid layered materials

Hod

2012

Phys. Rev. B

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Superlubricity is a frictionless tribological state sometimes occurring in nanoscale material junctions. It is often associated with incommensurate surface lattice structures appearing at the interface. Here, by using the recently introduced registry index concept which quantifies the registry mismatch in layered materials, we prove the existence of a direct relation between interlayer commensurability and wearless friction in layered materials. We show that our simple and intuitive model is able to capture, down to fine details, the experimentally measured frictional behavior of a hexagonal graphene flake sliding on-top of the surface of graphite. We further predict that superlubricity is expected to occur in hexagonal boron nitride as well with tribological characteristics very similar to those observed for the graphitic system. The success of our method in predicting experimental results along with its exceptional computational efficiency opens the way for modeling large-scale material interfaces way beyond the reach of standard simulation techniques.

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The tribological behavior of type II textured MX2 (M=Mo, W; X=S, Se) films

Cited by 64 publications

References 16 publications

Dissulfeto de molibdênio, um material multifuncional e surpreendente

Dissulfeto de molibdênio, um material multifuncional e surpreendente

Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS₂

Interlayer commensurability and superlubricity in rigid layered materials

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The tribological behavior of type II textured MX2 (M=Mo, W; X=S, Se) films

Cited by 64 publications

References 16 publications

Dissulfeto de molibdênio, um material multifuncional e surpreendente

Dissulfeto de molibdênio, um material multifuncional e surpreendente

Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS2

Interlayer commensurability and superlubricity in rigid layered materials

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Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS₂