Tsetseris and Pantelides Nanoscale Research Letters 2011, 6:245 NANO EXPRESS Open Access Defect-related hysteresis in nanotube-based nano-electromechanical systems Leonidas Tsetseris1,2*, Sokrates T Pantelides2,3,4 Abstract The electronic properties of multi-walled carbon nanotubes (MWCNTs) depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems (NEMS). In this article, we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes (DWCNTs) and their role in the response of the host systems under inter-tube displacement. Key defect-related effects, namely, sudden energy changes and hysteresis, are identified,. | Tsetseris and Pantelides Nanoscale Research Letters 2011 6 245 http content 6 1 245 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Defect-related hysteresis in nanotube-based nano-electromechanical systems Leonidas Tsetseris1 2 Sokrates T Pantelides2 3 4 Abstract The electronic properties of multi-walled carbon nanotubes MWCNTs depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems NEMS . In this article we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes DWCNTs and their role in the response of the host systems under inter-tube displacement. Key defect-related effects namely sudden energy changes and hysteresis are identified and their relevance to a host of MWCNT-based NEMS is highlighted. The results also demonstrate the dependence of these effects on defect clustering and chirality of DWCNT shells. Introduction The presence of point defects namely vacancies and selfinterstitials SI in modern carbonbased nano-materials has been the subject of intense research investigations 1-5 . These defects correspond to high-energy configurations which are not energetically favorable under thermal equilibrium. Nonetheless they can be formed as metastable structures because of non-equilibrium conditions during growth or under irradiation. Though they are typically harmful to device performance control over their formation can lead to defect engineering of novel structures with enhanced functionalities. One particular class of materials where point defects are expected to play an important role are nano-electromechanical systems NEMS that are based on multiwalled carbon nanotubes MWCNTs 6-12 . The relative displacement of MWCNT shells causes variation in the overlap of electronic states associated with neighboring tubes and change MWCNT .
