Surface effects on the persistence length of quasi-one-dimensional nanomaterials are investigated by using the theory of surface elasticity and the core-shell model of nanobeams. A simple and unified expression is pro...Surface effects on the persistence length of quasi-one-dimensional nanomaterials are investigated by using the theory of surface elasticity and the core-shell model of nanobeams. A simple and unified expression is provided to determine the persistence length of nanowires and nanotubes with any regular polygonal cross-sections. It is demonstrated that surface effects have a distinct in- fluence on the persistence length when the characteristic sizes of materials shrink to nanometers. This work is helpful not only for understanding the size-dependent behavior of nanomaterials but also for the design of devices based on nanotubes or nanowires.展开更多
Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we p...Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we perform molecular dynamics（MD） simulations to study the frictional behavior of a diamond tip sliding over a graphite surface. In contrast to the common wisdom, our MD results suggest that the energy barrier associated lateral sliding（known as energy corrugation） comes not only from interaction between the tip and the top layer of graphite but also from interactions among the deformed atomic layers of graphite. Due to the competition of these two subentries, friction on graphite can be tuned by controlling the relative adhesion of different interfaces.For relatively low tip-graphite adhesion, friction behaves normally and increases with increasing normal load. However,for relatively high tip-graphite adhesion, friction increases unusually with decreasing normal load leading to an effectively negative coefficient of friction, which is consistent with the recent experimental observations on chemically modified graphite. Our results provide a new insight into the physical origins of energy corrugation in atomic scale friction.展开更多
基金supported by the National Natural Science Foundation of China(11472035 and11432008)973 Program of MOST(2010CB631005 and 2012CB934001)
文摘Surface effects on the persistence length of quasi-one-dimensional nanomaterials are investigated by using the theory of surface elasticity and the core-shell model of nanobeams. A simple and unified expression is provided to determine the persistence length of nanowires and nanotubes with any regular polygonal cross-sections. It is demonstrated that surface effects have a distinct in- fluence on the persistence length when the characteristic sizes of materials shrink to nanometers. This work is helpful not only for understanding the size-dependent behavior of nanomaterials but also for the design of devices based on nanotubes or nanowires.
基金support from the National Natural Science Foundation of China (Grants 11272177, 11422218, 11432008)the National Basic Research Program of China (Grants 2013CB933003, 2013CB934201 and 2015CB351903)+2 种基金the Tsinghua University Initiative Scientific Research Programthe Thousand Young Talents Program of Chinathe financial support from China Postdoctoral Science Foundation (Grant 2014M562055)
文摘Although atomic stick–slip friction has been extensively studied since its first demonstration on graphite,the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we perform molecular dynamics（MD） simulations to study the frictional behavior of a diamond tip sliding over a graphite surface. In contrast to the common wisdom, our MD results suggest that the energy barrier associated lateral sliding（known as energy corrugation） comes not only from interaction between the tip and the top layer of graphite but also from interactions among the deformed atomic layers of graphite. Due to the competition of these two subentries, friction on graphite can be tuned by controlling the relative adhesion of different interfaces.For relatively low tip-graphite adhesion, friction behaves normally and increases with increasing normal load. However,for relatively high tip-graphite adhesion, friction increases unusually with decreasing normal load leading to an effectively negative coefficient of friction, which is consistent with the recent experimental observations on chemically modified graphite. Our results provide a new insight into the physical origins of energy corrugation in atomic scale friction.
