Nanoscale Lubrication of Ionic Surfaces Controlled via a Strong Electric Field

Strelcov, Evgheni; Kumar, Rajeev; Bocharova, Vera; Sumpter, Bobby G.; Tselev, Alexander; Kalinin, Sergei V.

doi:10.1038/srep08049

Cited by 25 publications

(19 citation statements)

References 26 publications

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“…The author described the frequency dependence of friction in terms of the dynamic conformal change of PE ionization under the electric field. Recently, Strelcov et al reported that boundary lubrication properties can be actively controlled between an AFM tip and a salt surface when the relative humidity is above a certain threshold and a sufficiently strong electric field is applied [132]. A plausible mechanism was proposed that an ordered structure of electric double layer as a result of water condensation and dissolution of polarizable ions accounts for the reduction of friction force.…”

Section: Other Approaches For Active Control Of Boundary Lubricationmentioning

confidence: 99%

Boundary lubrication by adsorption film

2015

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A complete understanding of the mechanism of boundary lubrication is a goal that scientists have been striving to achieve over the past century. Although this complicated process has been far from fully revealed, a general picture and its influencing factors have been elucidated, not only at the macroscopic scale but also at the nanoscale, which is sufficiently clear to provide effective instructions for a lubrication design in engineering and even to efficiently control the boundary lubrication properties. Herein, we provide a review on the main advances, especially the breakthroughs in uncovering the mysterious but useful process of boundary lubrication by adsorption film. Despite the existence of an enormous amount of knowledge, albeit unsystematic, acquired in this area, in the present review, an effort was made to clarify the mainline of leading perspectives and methodologies in revealing the fundamental problems inherent to boundary lubrication. The main content of this review includes the formation of boundary film, the effects of boundary film on the adhesion and friction of rough surfaces, the behavior of adsorption film in boundary lubrication, boundary lubrication at the nanoscale, and the active control of boundary lubrication, generally sequenced based on the real history of our understanding of this process over the past century, incorporated by related modern concepts and prospects.

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Section: Other Approaches For Active Control Of Boundary Lubricationmentioning

confidence: 99%

Boundary lubrication by adsorption film

2015

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“…Both observations [88,92] indicate clearly that the positively charged (H + ) tip or substrate (electronic holes +) would induce high friction force [23].…”

Section: Quantum Friction: Charging and Isotopic Phonon Effectmentioning

confidence: 99%

“…In 1989, Krim and coworkers [6] found the friction coefficient of Krypton films on crystalline gold surfaces is lower when dry; adding a liquid film raises the coefficient by five times, instead. Applying electric field cross the contacting interface can also affect the coefficient of friction [23].…”

Section: Interface Phonons and Electronsmentioning

confidence: 99%

From ice superlubricity to quantum friction: Electronic repulsivity and phononic elasticity

Zhang

Huang

et al. 2015

Friction

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Superlubricity means non-sticky and frictionless when two bodies are set contacting motion. Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice, the mechanism behind the superlubricity remains uncertain. This report features a consistent understanding of the superlubricity pertaining to the slipperiness of ice, self-lubrication of dry solids, and aqueous lubricancy from the perspective of skin bond-electron-phonon adaptive relaxation. The presence of nonbonding electron polarization, atomic or molecular undercoordination, and solute ionic electrification of the hydrogen bond as an addition, ensures the superlubricity. Nonbond vibration creates soft phonons of high magnitude and low frequency with extraordinary adaptivity and recoverability of deformation. Molecular undercoordination shortens the covalent bond with local charge densification, which in turn polarizes the nonbonding electrons making them localized dipoles. The locally pinned dipoles provide force opposing contact, mimicking magnetic levitation and hovercraft. O:H−O bond electrification by aqueous ions has the same effect of molecular undercoordination but it is throughout the entire body of the lubricant. Such a Coulomb repulsivity due to the negatively charged skins and elastic adaptivity due to soft nonbonding phonons of one of the contacting objects not only lowers the effective contacting force but also prevents charge from being transited between the counterparts of the contact. Consistency between theory predictions and observations evidences the validity of the proposal of interface elastic Coulomb repulsion that serves as the rule for the superlubricity of ice, wet and dry frictions, which also reconciles the superhydrophobicity, superlubricity, and supersolidity at contacts.

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“…A similar setup is used for nanometer-scale material modifications [9][10][11]. Concentrated electric fields developed during voltage application in the tip-sample junction in a volume of a few tens of nanometers in size can be extremely strong -in excess of 10 8 V/m, which has been utilized to explore phenomena and material behaviors in strong electric fields, for example, nanoscale melting [12], electric-field-induced water condensation [13,14], water dissociation [15], nanoscale lubrication [16], and ionic conduction [17]. Such studies would highly benefit from knowledge of the electric field strength at the tip-sample contact through providing well-controlled stimulus as well as for correct interpretation and modeling of results.…”

Section: Introductionmentioning

confidence: 99%

“…Observation of effects associated with the large electric field in the tip-sample junction indirectly proves the large strength of the field (see, e.g., refs. [9,13,14,16]). However, currently there are no methods, which would allow measuring the electric field strength in the junction.…”

Section: Introductionmentioning

confidence: 99%

Quantification of in-contact probe-sample electrostatic forces with dynamic atomic force microscopy

et al. 2017

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Atomic Force Microscopy (AFM) methods utilizing resonant mechanical vibrations of cantilevers in contact with a sample surface have shown sensitivities as high as few picometers for detecting surface displacements. Such a high sensitivity is harnessed in several AFM imaging modes. Here, we demonstrate a cantilever-resonance-based method to quantify electrostatic forces on a probe arising in the presence of a surface potential or when a bias voltage is applied to the AFM probe.We find that the electrostatic forces acting on the probe tip apex can strongly dominate cantilever response in electromechanical measurements and produce signals equivalent to few pm of surface displacement. In combination with modeling, the measurements of the force were used to determine the strength of the electrical field at the probe tip apex in contact with a sample. We find an evidence that the electric field strength in the junctions is limited by about 0.5 V/nm. This field 2 can be sufficiently strong to significantly influence material states and kinetic processes through charge injection, Maxwell stress, shifts of phase equilibria, and reduction of energy barriers for activated processes. Besides, the results provide a baseline for accounting for the effects of local electrostatic forces in electromechanical AFM measurements as well as offer additional means to probe ionic mobility and field-induced phenomena in solids.

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Nanoscale Lubrication of Ionic Surfaces Controlled via a Strong Electric Field

Cited by 25 publications

References 26 publications

Boundary lubrication by adsorption film

Boundary lubrication by adsorption film

From ice superlubricity to quantum friction: Electronic repulsivity and phononic elasticity

Quantification of in-contact probe-sample electrostatic forces with dynamic atomic force microscopy

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