Speaker
Description
Study of friction and energy dissipation always relied on direct observations. Actual theories provide limited prediction on the frictional and dissipative properties if only the material chemistry and geometry are known. We here develop a framework to study intrinsic friction and energy dissipation based on the only knowledge of the normal modes of the system at the equilibrium. To this aim, we conducted quantum-mechanic based investigation on prototypical TMDs. We combined the structural and dynamic information from group theoretical analysis and phonon band structure calculations with the characterisation of the electronic features using non-standard methods such us orbital polarization [1] and the recently formulated bond covalency [2] and cophonicity [3] analyses. We outline phonon-scattering selection rules [4], and propose a phonon-mode based method, named Normal-Modes Transition Approximation [5], to identify possible sliding paths from only the analysis of the phonon modes of the stable geometry and to tune the corresponding sliding energy barriers. We show how to characterize the frequency content of observed physical quantities [6-7] and individuate the dissipative processes active during experimental measurements. As a case study, we consider the relative sliding motion of atomic layers in transition metal dichalcogenides (TMDs) dry lubricant, and discuss how to extract information on the potential energy landscape from Atomic Force Microscopy signals.
The presented framework switches the investigation paradigm on friction and energy dissipation from dynamic to static studies, paving new avenues to explore for the design of novel anisotropic tribological and thermal materials [8-10]. Finally, thanks to the general formulation of our approaches, the present outcomes can be promptly used to finely tune physical properties for the design of new materials with diverse applications beyond tribology.
The present research has been published in impacted scientific journals and received support from the GACR and Horizon-2020 funding bodies.
References
[1] A. Cammarata et al. “Octahedral Engineering of Orbital Polarizations in Charge Transfer Oxides”, Physical Review B 87, 155135 (2013)
[2] A. Cammarata et al. “Covalent Dependence of Octahedral Rotations in Orthorhombic Perovskite Oxides, The Journal of Physical Chemistry 141, 114704 (2014)
[3] A. Cammarata et al. “Tailoring Nanoscale Friction in MX2 Transition Metal Dichalcogenides”, Inorganic Chemistry 54, 5739 (2015)
[4] A. Cammarata “Phonon–phonon Scattering Selection Rules And Control: An Application To Nanofriction And Thermal Transport” RSC Advances 9, 37491 (2019)
[5] A. Cammarata et al. “Overcoming Nanoscale Friction Barriers In Transition Metal Dichalcogenides”, Physical Review B 96, 085406 (2017)
[6] A. Cammarata et al. “Atomic-scale Design Of Friction And Energy Dissipation”, Physical Review B 99, 094309 (2019)
[7] A. Cammarata et al. “Control Of Energy Dissipation In Sliding Low-Dimensional Materials”, Physical Review B 102, 085409 (2020)
[8] A. Cammarata et al. “Fine control of lattice thermal conductivity in low-dimensional materials”, Physical Review B 103, 035406 (2021).
[9] A. Cammarata et al. “Effect of Noninteracting Intercalants on Layer Exfoliation in Transition-Metal Dichalcogenides”, Physical Review Applied 15, 064041 (2021)
[10] B. Perotti, A. Cammarata et al. “Phototribology: Control of Friction by Light”, ACS Appl. Mater. Interfaces 13, 43746 (2021)
