Structural Superlubricity Based on Crystalline Materials.

Herein, structural superlubricity, a fascinating phenomenon where the friction is ultralow due to the lateral interaction cancellation resulted from incommensurate contact crystalline surfaces, is reviewed. Various kinds of nano- and microscale materials such as 2D materials, metals, and compounds are used for the fabrication. For homogeneous frictional pairs, superlow friction forces exist in most relative orientations with incommensurate configuration. Heterojunctions bear no resemblance to homogeneous contact, since the lattice constants are naturally mismatched which leads to a robust structural superlubricity with any orientation of the two different surfaces. A discussion on the perspectives of this field is also provided to meet the existing challenges and chart the future.