Tag Archives: friction

Temperature effects on the nano-friction across exposed atomic step edges

In the article “Temperature effects on the nano-friction across exposed atomic step edges” Wen Wang, Ashu Wang and Lingyan Zeng describe how they used friction force microscopy ( FFM ) under ultrahigh vacuum ( UHV) conditions to study the temperature dependence of nanoscale friction between a silicon AFM tip ( NANOSENSORS™ PointProbe® Plus PPP-LFMR AFM probe for lateral/friction force microscopy ) and a freshly cleaved HOPG surface with exposed single- and double-layer step edges.*

They present experimental measurements as well as theoretical calculations of the temperature effects on atomic friction across HOPG surface step edges.*

Among other things the authors found that the resistive force for the double-layer step edge was twice as large as that of the single-step edge, and simultaneously, the assistive force that resulted from the horizontal component of the total force acting on the AFM tip seemed to be less influenced by the height of the step edges.*

Their experimental results also showed that temperature had very little effect on the friction coefficients at the step edges, which is inconsistent with the thermal activated friction where friction should decrease with temperature.*

Based on the theoretical studies, this observation can be explained by a process where the temperature effect is very small compared with the edge Schwoebel–Ehrlich barrier.*

The authors hope that their findings will contribute to understanding the temperature effects on macroscopic friction having a lot of step edges at the interface.*

Figure 1 from “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang et al.:
 Experimental setup and the topographic image of the HOPG surface with step edges used in our measurements. (a) Illustration of the experimental setup. All experiments have been performed using a conventional friction force microscope on a freshly cleaved HOPG sample which was in contact with the temperature control stage under UHV conditions. (b) The typical topographic image of the HOPG surface with a single- and double-layer step edge obtained at T = 297.7 K using the contact mode operation with an applied normal force of 13.1 nN and a scan velocity of 1.25 μm/s. (c) The cross-section height profile across the step edges highlighted in (b). The black arrows in (b) and (c) indicate the scanning direction.  NANOSENSORS PointProbe Plus PPP-LFMR AFM probes for lateral force microscopy and friction force microscopy were used.
Figure 1 from “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang et al.:
 Experimental setup and the topographic image of the HOPG surface with step edges used in our measurements. (a) Illustration of the experimental setup. All experiments have been performed using a conventional friction force microscope on a freshly cleaved HOPG sample which was in contact with the temperature control stage under UHV conditions. (b) The typical topographic image of the HOPG surface with a single- and double-layer step edge obtained at T = 297.7 K using the contact mode operation with an applied normal force of 13.1 nN and a scan velocity of 1.25 μm/s. (c) The cross-section height profile across the step edges highlighted in (b). The black arrows in (b) and (c) indicate the scanning direction.

*Wen Wang, Ashu Wang and Lingyan Zeng
Temperature effects on the nano-friction across exposed atomic step edges
AIP Advances 10, 085322 (2020)
DOI: https://doi.org/10.1063/5.0019196

Please follow this external link to read the full article: https://aip.scitation.org/doi/10.1063/5.0019196

Open Access The article “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang, Ashu Wang and Lingyan Zeng is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Insights into dynamic sliding contacts from conductive atomic force microscopy

Friction in nanoscale contacts is determined by the size and structure of the interface that is hidden between the contacting bodies. One approach to investigating the origins of friction is to measure electrical conductivity as a proxy for contact size and structure. However, the relationships between contact, friction and conductivity are not fully understood, limiting the usefulness of such measurements for interpreting dynamic sliding properties.*

In their study “Insights into dynamic sliding contacts from conductive atomic force microscopy” Nicholas Chan, Mohammad R. Vazirisereshk, Ashlie Martini and Philip Egberts used atomic force microscopy (AFM) to simultaneously acquire lattice resolution images of the lateral force and current flow through the tip–sample contact formed between a highly oriented pyrolytic graphite (HOPG) sample and a conductive diamond AFM probe to explore the underlying mechanisms and correlations between friction and conductivity. Both current and lateral force exhibited fluctuations corresponding to the periodicity of the HOPG lattice.

Unexpectedly, while lateral force increased during stick events of atomic stick-slip, the current decreased exponentially.*

The results presented in the study by Nicholas Chan et al. confirm that the correlation between conduction and atom–atom distance previously proposed for stationary contacts can be extended to sliding contacts in the stick-slip regime.*

A NANOSENSORS™ conductive diamond coated AFM probe CDT-CONTR was used to obtain all experimental data presented in their manuscript.*

Figure 1 (a) from “Insights into dynamic sliding contacts from conductive atomic force microscopy” by Nicholas Chan et al:
A schematic of the experimental setup is shown in Fig. 1(a). The experiment was conducted using an ultra-high vacuum (UHV) (RHK) AFM at room temperature at a pressure of <1109Torr. A doped diamond coated cantilever (NANOSENSORS CDT-CONTR) with a normal bending spring constant of 0.86 N m1and lateral spring constant of 10 N m1was used to obtain all experimental data presented in this manuscript.

Figure 1 (a) from “Insights into dynamic sliding contacts from conductive atomic force microscopy” by Nicholas Chan et al:
A schematic of the experimental setup is shown in Fig. 1(a). The experiment was conducted using an ultra-high vacuum (UHV)AFM at room temperature at a pressure of <1109Torr. A doped diamond coated cantilever (NANOSENSORS CDT-CONTR) with a normal bending spring constant of 0.86 N m1and lateral spring constant of 10 N m1was used to obtain all experimental data presented in this manuscript.

*Nicholas Chan, Mohammad R. Vazirisereshk, Ashlie Martini and Philip Egberts
Insights into dynamic sliding contacts from conductive atomic force microscopy
Nanoscale Advances., 2020, Advance Article
DOI: 10.1039/d0na00414f

Please follow this external link to read the whole article: https://pubs.rsc.org/en/content/articlepdf/2020/na/d0na00414f

Open Access: The article “Insights into dynamic sliding contacts from conductive atomic force microscopy” by Nicholas Chan, Mohammad R. Vazirisereshk, Ashlie Martini and Philip Egberts is licensed under a Creative Commons Attribution 3.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/.