About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
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Symposium
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Mechanical Behavior at the Nanoscale VI
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Presentation Title |
Visualizing Nanoscale Contacts In Situ: History-dependent Adhesion of Si-Si and MoS2-MoS2 Interfaces |
Author(s) |
Robert Carpick |
On-Site Speaker (Planned) |
Robert Carpick |
Abstract Scope |
I will discuss nanocontact experiments conducted using an in situ nanoindentation apparatus inside a transmission electron microscope (TEM). The instrument is customized to permit atomic-scale imaging of contact formation, asperity sliding, and adhesive separation of two nanoasperities with real-time TEM imaging. Forming and separating Si-Si nanocontacts without sliding revealed small adhesion forces; sliding before retraction resulted in a nearly 20 times increase in adhesion. This reversible sliding-dependent adhesion is attributed to removal of passivating species from the surfaces, followed by their re-adsorption after separation [https://doi.org/10.1021/acs.langmuir.9b02029]. Molecular dynamics (MD) simulations support this idea and further elucidate processes occurring at the interface [https://doi.org/10.1007/s11249-021-01431-z]. I will also discuss nanocontact experiments of 2D materials using this instrument. For tip-on-tip contacts of few-layer MoS2, adhesion increases with successive cycles of contact, far exceeding values expected for pure van der Waals interfacial interactions. Combined with MD, this effect is attributed to contact-induced defect formation. |
Proceedings Inclusion? |
Planned: |
Keywords |
Nanotechnology, Thin Films and Interfaces, Other |