Mechanical properties of C60 single crystals

Fomenko, L. S.; Lubenets, S. V.; Izotov, A. N.; Nikolaev, R. K.; Sidorov, N. S.

doi:10.1016/j.msea.2005.01.068

Cited by 5 publications

(2 citation statements)

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“…The local concentration of C 60 in the gap therefore increases as the surfaces approach, and the C 60 moleculeswhich are already close to the aggregation limit in the bulk solutionare expected to agglomerate, forming a strongly bound solid film (as shown by the soft wall in the normal force profile). The fact that this film holds for pressures up to ∼6 MPa is remarkable, given that a yield stress of about ∼1 MPa is measured when compressing a C 60 single crystal along the ⟨1 1 0⟩ direction . This is probably due to the fact that we are dealing with a nanometric film with the C 60 having attractive interactions with the confining surfaces and being packed in a disordered arrangement with no cleaving plane.…”

Section: Discussionmentioning

confidence: 99%

“…The fact that this film holds for pressures up to ∼6 MPa is remarkable, given that a yield stress of about ∼1 MPa is measured when compressing a C 60 single crystal along the ⟨1 1 0⟩ direction. 43 This is probably due to the fact that we are dealing with a nanometric film with the C 60 having attractive interactions with the confining surfaces and being packed in a disordered arrangement with no cleaving plane.…”

Section: ■ Methodsmentioning

confidence: 99%

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Are Buckminsterfullerenes Molecular Ball Bearings?

et al. 2018

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Buckminsterfullerenes (C 60) are near-spherical 2 molecules which freely rotate at room temper-3 ature in the solid state and when dissolved in 4 solution. An intriguing question arises as to 5 whether C 60 molecules can act as molecular 6 ball bearings, i.e. preventing direct contact 7 between two solid surfaces whilst simultane-8 ously dissipating shear stress through fast ro-9 tation. To explore this, we performed measure-10 ments of friction across a solution of C 60 in the 11 boundary lubrication regime. High resolution 12 shear and normal force measurements between 13 mica sheets separated by the C 60 solution were 14 made using a Surface Force Balance to provide a 15 single-asperity contact and sub-nanometer res-16 olution in lm thickness. We nd that, even 17 at small volume fraction, C 60 forms a solid-like 18 amorphous boundary lm sustaining high nor-19 mal load, suggesting that this system undergoes 20 a glass transition under connement. The C 60 21 lm gives rise to a low friction coecient up 22 to moderate applied loads, and we discuss the 23 possible relevance of the ball bearing eect at 24 the molecular scale. 25 2 Ball bearings, consisting of 40 balls running along a groove (e.g. in an axle 41 assembly), are designed to reduce the friction 42 further by transforming sliding into rolling. It 43

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Section: Discussionmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Are Buckminsterfullerenes Molecular Ball Bearings?

et al. 2018

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Low-temperature mechanical properties of fullerites: structure, elasticity, plasticity, strength

Lubenets

Fomenko

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et al. 2019

Low Temperature Physics

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The results of long-term studies on the physical-mechanical properties of C60 and C70 molecular crystals (fullerites) were systematized and described. These materials are the new allotropic form of carbon in which fullerenes (stable molecules consisting of 60 and 70 atoms) represent the elementary base units. Molecules are combined into crystalline structures mainly by dispersive (van der Waals) forces with a small contribution from covalent bonds. The anomalies of the fullerite crystal structures and features of the phase transitions occurring in them, which are caused by dispersive forces, orientation ordering, and dynamics of the molecules’ rotational degrees of freedom, were discussed. The most interesting transformations of fullerite lattice structures and orientation states were observed in the temperature range of 77 K ≲ Т ≲ 350 K. The majority of the experimental investigations were carried out at these temperatures. The experiments were concentrated on the effects that lattice-orientation phase transitions had on the mechanical properties of single crystals, polycrystalline solids, and compacts. Acoustical spectroscopy at low and high oscillation frequencies, micro- and nanoindentation and macrodeformation methods were used in the experimental research. The crystallogeometric aspects and dislocation mechanisms of plastic slip in fullerites, as well as the methods of observing dislocations and studying their mobility, are described in detail. Also the influence of different external factors, namely, illumination (photoplastic effect), pulsed magnetic field (magnetoplastic effect), and sample compaction pressure (baropolymerization effect) are discussed. The effects of saturating samples of different morphology with hydrogen, oxygen, and inert gas impurities on the fullerites’ mechanical properties were considered. The discussion of the experimental results is accompanied by a brief description of their theoretical interpretation based on analyzing the interaction of elastic and plastic deformations of the fullerite lattice with the processes of orientational ordering, rotation, and librational vibrations of molecules.

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