17 research outputs found
Interaction imaging with amplitude-dependence force spectroscopy
Knowledge of surface forces is the key to understanding a large number of
processes in fields ranging from physics to material science and biology. The
most common method to study surfaces is dynamic atomic force microscopy (AFM).
Dynamic AFM has been enormously successful in imaging surface topography, even
to atomic resolution, but the force between the AFM tip and the surface remains
unknown during imaging. Here, we present a new approach that combines high
accuracy force measurements and high resolution scanning. The method, called
amplitude-dependence force spectroscopy (ADFS) is based on the
amplitude-dependence of the cantilever's response near resonance and allows for
separate determination of both conservative and dissipative tip-surface
interactions. We use ADFS to quantitatively study and map the nano-mechanical
interaction between the AFM tip and heterogeneous polymer surfaces. ADFS is
compatible with commercial atomic force microscopes and we anticipate its
wide-spread use in taking AFM toward quantitative microscopy
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Speed dependence of friction on single-layer and bulk MoS2 measured by atomic force microscopy
We perform atomic force microscopy (AFM) experiments on mechanically exfoliated, single-layer and bulk molybdenum disulfide (MoS2) in order to probe friction forces as a function of sliding speed. The results of the experiments demonstrate that (i) friction forces increase logarithmically with respect to sliding speed, (ii) there is no correlation between the speed dependence of friction and the number of layers of MoS2, and (iii) changes in the speed dependence of friction can be attributed to changes in the physical characteristics of the AFM probe, manifesting in the form of varying contact stiffness and tip-sample interaction potential parameters in the thermally activated Prandtl-Tomlinson model. Our study contributes to the formation of a mechanistic understanding of the speed dependence of nanoscale friction on two-dimensional materials
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Emerging superlubricity: A review of the state of the art and perspectives on future research
We present a review of superlubricity: the state of ultra-low friction between surfaces in relative motion. Various approaches to achieving this state are considered in a broad sense, including structural superlubricity, superlubricity via normal force control, and contact actuation, as well as thermolubricity, liquid superlubricity, and quantum lubricity. An overview of the physical fundamentals associated with each approach is presented, with particular emphasis on recent theoretical and experimental developments that constitute milestones in our scientific understanding. The review also includes a discussion of perspectives on future research in the context of existing challenges. It is projected that interest in superlubricity from the basic science and engineering communities will continue to accelerate in the near future, accompanied by a transition from fundamental studies to technologically relevant applications
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Solid lubrication with MoS2: A review
Molybdenum disulfide (MoS2) is one of the most broadly utilized solid lubricants with a wide range of applications, including but not limited to those in the aerospace/space industry. Here we present a focused review of solid lubrication with MoS2 by highlighting its structure, synthesis, applications and the fundamental mechanisms underlying its lubricative properties, together with a discussion of their environmental and temperature dependence. The review also includes an extensive overview of the structure and tribological properties of doped MoS2, followed by a discussion of potential future research directions
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The potential of Ti3C2Tx nano-sheets (MXenes) for nanoscale solid lubrication revealed by friction force microscopy
TiCT nano-sheets (MXenes) are an emerging class of
two-dimensional materials with outstanding potential to be employed in energy
storage, catalysis, and triboelectric applications, on length scales ranging
from the nano- to macroscopic. Despite rapidly accelerating interest in this
new class of materials, their nanoscale frictional properties and in
particular, their potential for solid lubrication on the nanoscale, have not
been explored in detail yet. In this short communication, we present the first
results on the nanoscale frictional characteristics of MXenes, in the form of a
friction map obtained on an isolated TiCT nano-sheet deposited on a
silicon dioxide substrate via friction force microscopy. Our experiments reveal
that few-layer TiCT nano-sheets indeed act as solid lubricants on
the nanoscale, reducing friction on the silicon dioxide substrates, although
not as effectively as few-layer graphene. The results reported here pave the
way for further studies focusing on nanoscale solid lubrication achieved by
TiCT (MXene) nano-sheets
The emergence of multifrequency force microscopy
Atomic force microscopy uses the deflection of a cantilever with a sharp tip to
examine surfaces, and conventional dynamic force microscopy involves the
excitation and detection of a single frequency component of the tip’s motion.
Information about the properties of a sample is, however, encoded in the motion
of the probe and the dynamics of the cantilever are highly nonlinear. Therefore,
information included in the other frequency components is irreversibly lost.
Multifrequency force microscopy involves the excitation and/or detection of
several frequencies of the probe’s oscillation, and has the potential to overcome
limitations in spatial resolution and acquisition times of conventional force
microscopes. It could also provide new applications in fields such as energy
storage and nanomedicine. Here we review the development of multifrequency
force microscopy methods, highlighting the five most prominent approaches. We
also examine the range of applications offered by the technique, which include
mapping the flexibility of proteins, imaging the mechanical vibrations of carbonbased
resonators, mapping ion diffusion, and imaging the subsurface of cells.We are grateful for financial support from the Ministerio de Ciencia e Innovación (CSD2010-00024, MAT2009-08650).Peer reviewe