Filtering Robust Graphite without Incommensurate Interfaces by Electrical Technique

Two-dimensional (2D) van der Waals (vdW) layered materials have attracted considerable attention due to their potential applications in various fields. Among these materials, graphite is widely employed to achieve structural superlubricity (SSL), where the interfacial friction between two solids is almost negligible and the wear is zero. However, the development of integrated SSL systems using graphite flakes still faces a major obstacle stemming from the inherent delamination-induced instability in vdW layered materials. To address this issue, we propose a nondestructive filtering technique that utilizes electrical measurement to identify robust graphite flakes without delamination. Our experimental results confirm that all the filtered graphite flakes exhibit delamination-free behavior after more than 7000 cycles of sliding on a series of 2D and 3D substrates. Besides, we employ three types of characterizing methods to confirm that the filtering process does not impair the graphite flakes. Moreover, with focused ion beam (FIB) assisted slicing characterization and statistical analysis, we have discovered that all of the filtered flakes possess a graphite layer thickness below 100 nm. This is consistent with the thickness of the single crystalline graphite layer of our samples reported in the literature, suggesting the absence of incommensurate interfaces in the filtered graphite flakes. Our work contributes to a deeper understanding of the relationship between graphite conductance and incommensurate interfaces. In addition, we present a possible solution to address the delamination problem in layered materials, and this technique shows the potential to characterize the internal microstructure of grains and the distribution of grain boundaries in vdW materials on a large scale.

Automated summary

This paper introduces a nondestructive filtering technique that utilizes electrical measurement to identify stable graphite flakes and confirms their delamination-free behavior. The study also discovers that the thickness of the filtered flakes is consistent with the single crystalline graphite layer thickness, suggesting the absence of incommensurate interfaces. This technique provides a possible solution to the delamination problem in layered materials and shows the potential to characterize the microstructure of vdW materials on a large scale.