Nanotribological studies using nanoparticle manipulation: Principles and application to structural lubricity

摘要

The term "structural lubricity" denotes a fundamental concept where the friction between two atomically flat surfaces is reduced due to lattice mismatch at the interface. Under favorable circumstances, its effect may cause a contact to experience ultra-low friction, which is why it is also referred to as "superlubricity". While the basic principle is intriguingly simple, the experimental analysis of structural lubricity has been challenging. One of the main reasons for this predicament is that the tool most frequently used in nanotribology, the friction force microscope, is not well suited to analyse the friction of extended nanocontacts. To overcome this deficiency, substantial efforts have been directed in recent years towards establishing nanoparticle manipulation techniques, where the friction of nanoparticles sliding on a substrate is measured, as an alternative approach to nanotribological research. By choosing appropriate nanoparticles and substrates, interfaces exhibiting the characteristics needed for the occurrence of structural lubricity can be created. As a consequence, nanoparticle manipulation experiments such as in this review represent a unique opportunity to study the physical conditions and processes necessary to establish structural lubricity, thereby opening a path to exploit this effect in technological applications.