Atomistic simulation of frictional anisotropy on quasicrystal approximant surfaces

Ye, Zhijiang; Martini, Ashlie; Thiel, Patricia A.; Lovelady, Heather H.; McLaughlin, K. L.; Rabson, David

doi:10.1103/physrevb.93.235438

“…The contrast may also be enhanced by the presence of chains adsorbed at the tip apex, as suggested by the results in Ref. [17] as well as in recent work by Pawlak et al [56]. Considering the variety of liquid environments and of physical-chemical conditions which could be addressed in this way (see, e.g., the dynamics of surface reconstructions of metals in electrochemical cells [57,58]), our results are potentially far reaching and could impact the understanding of friction anisotropy and its relation to the surface microstructure.…”

Section: Discussionmentioning

confidence: 74%

“…In contrast, when the shear direction is perpendicular to the backbones, friction and wear increase due to molecular reorientation. MD simulations have been also reported on quasicrystal surfaces by Ye et al, who, interestingly, could recover friction anisotropy only after passivating the probing tip with chains of hexadecane thiol [17].…”

Section: Introductionmentioning

confidence: 77%

Molecular-scale shear response of the organic semiconductor β -DBDCS (100) surface

Álvarez-Asencio

¹

,

Moreno-Ramírez

²

,

Pimentel

³

et al. 2017

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In this work we present friction-force microscopy (FFM) lattice-resolved images acquired on the (100) facet of the semiconductor organic oligomer (2Z,2 Z) − 3,3 -(1,4-phenylene)bis(2-(4-butoxyphenyl)acrylonitrile) (β-DBDCS) crystal in water at room temperature. Stick-slip contrast, lateral contact stiffness, and friction forces are found to depend strongly on the sliding direction due to the anisotropic packing of the molecular chains forming the crystal surface along the [010] and [001] directions. The anisotropy also causes the maximum value of the normal force applicable before wearing to increase by a factor of 3 when the scan is performed along the [001] direction on the (100) face. Altogether, our results contribute to achieving a better understanding of the molecular origin of friction anisotropy on soft crystalline surfaces, which has been often hypothesized but rarely investigated in the literature.

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“…Nano-and microelectromechanical system (NEMS and MEMS) switches are potential next-generation electronic computing devices that could offer improved computational efficiency, due to their small scale, low power consumption, and high speed [1][2][3][4][5][6][7]. Different from complementary metal-oxide semiconductor (CMOS) transistors, the on and off states of NEMS and MEMS are modulated by the closing and opening of the contacts, which could bridge the source and drain terminals into a closed circuit.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Benzene Tribopolymerization on the RuO2 (110) Surface

Yang

¹

,

Qi

²

,

Kim

³

et al. 2018

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Tribopolymer formed on the contacts of microelectromechanical and nanoelectromechanical system (MEMS/NEMS) devices is a major concern hampering their practical use in information technology. Conductive metal oxides, such as RuO 2 and ReO 3 , have been regarded as promising candidate materials for MEMS/NEMS contacts due to their conductivity, hardness, and relatively chemically inert surfaces. However, recent experimental works demonstrate that trace amounts of polymer could still form on RuO 2 surfaces. In this study, we demonstrate the mechanism of this class of unexpected tribopolymer formation by conducting density functional theory based computational compression experiments with benzene as the contamination gas. First, mechanical force during compression changes the benzene molecules from slightly physisorbed to strongly chemisorbed. Further compression causes deformation and chemical linkage of the benzene molecules. Finally, the two contacts detach, with one having a complex organic molecule attached and the other with a more reactive surface. The complex organic molecule, which has an oxabicyclic segment, can be viewed as the rudiment of tribopolymer, and the more reactive surface can trigger the next adsorption-reaction-tribopolymer formation cycle. Based on these results, we also predict tribopolymer formation rates by using transition-state theory and the second-order rate law. This study deepens our understanding of tribopolymer formation (especially on metal oxides) and provides strategies for suppressing tribopolymerization.

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“…Nano-and microelectromechanical system (NEMS and MEMS) switches are potential nextgeneration electronic computing devices that could offer improved computational efficiency, due to their small scale, low power consumption, and high speed. [1][2][3][4][5][6][7] Different from complementary metal-oxide semiconductor (CMOS) transistors, the on and off states of NEMS and MEMS are modulated by the closing and opening of the contacts, which could bridge the source and drain terminals into a closed circuit. In such an operation, there is essentially no open-circuit leakage or energy dissipation.…”

Section: Introductionmentioning

confidence: 99%

Tribopolymer Formation Mechanism on the RuO$_2$(110) Surface

Yang,

Qi,

Kim

et al. 2017

Preprint

0

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Tribopolymer formed on the contacts of microelectromechanical and nanoelectromechanical system (MEMS/NEMS) devices is a major concern hampering their practical use in information technology. Conductive metal oxides, such as RuO 2 and ReO 3 , have been regarded as promising candidate materials for MEMS/NEMS contacts due to their conductivity, hardness, and relatively chemically inert surfaces. However, recent experimental works demonstrate that trace amounts of polymer could still form on RuO 2 surfaces. In this study, we demonstrate the mechanism of this class of unexpected tribopolymer formation by conducting density functional theory based computational compression experiments with benzene as the contamination gas. First, mechanical force during compression changes the benzene molecules from slightly physisorbed to strongly chemisorbed. Further compression causes deformation and chemical linkage of the benzene molecules. Finally, the two contacts detach, with one having a complex organic molecule attached and the other with a more reactive surface. The complex organic molecule, which has an oxabicyclic segment, can be viewed as the rudiment of

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Atomistic simulation of frictional anisotropy on quasicrystal approximant surfaces

Cited by 6 publications

References 46 publications

Molecular-scale shear response of the organic semiconductor β -DBDCS (100) surface

Molecular-scale shear response of the organic semiconductor β -DBDCS (100) surface

Mechanism of Benzene Tribopolymerization on the RuO2 (110) Surface

Tribopolymer Formation Mechanism on the RuO$_2$(110) Surface

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