| AVS 64th International Symposium & Exhibition | |
| Tribology Focus Topic | Wednesday Sessions |
| Session TR+AS+HI+NS+SS-WeA |
| Session: | Molecular Origins of Friction |
| Presenter: | Paul Sheehan, US Naval Research Laboratory |
| Authors: | P.E. Sheehan, US Naval Research Laboratory CM. Lieber, Harvard University |
| Correspondent: | Click to Email |
Nanometer-scale crystals of the 2D oxide molybdenum trioxide (MoO3) were formed atop the transition metal dichalcogenides MoS2 and MoSe2. The MoO3 nanocrystals are partially commensurate with the dichalcogenide substrates, being aligned only along one of the substrate’s crystallographic axes. These nanocrystals can be slid only along the aligned direction and maintain their alignment with the substrate during motion. Using an AFM probe to oscillate the nanocrystals, it was found that the lateral force required to move them increased linearly with nanocrystal area. The slope of this curve, the interfacial shear strength, was significantly lower than for macroscale systems. It also depended strongly on the duration and the velocity of sliding of the crystal, suggesting a thermal activation model for the system. Finally, it was found that lower commensuration between the nanocrystal and the substrate increased the interfacial shear, a trend opposite that predicted theoretically.