Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Do Twin Boundaries Always Strengthen Metal Nanowires? | Nanoscale Res Lett 2009 4 34-38 DOI S11671-008-9198-1 NANO EXPRESS Do Twin Boundaries Always Strengthen Metal Nanowires Yongfeng Zhang Hanchen Huang Received 1 October 2008 Accepted 22 October 2008 Published online 11 November 2008 to the authors 2008 Abstract It has been widely reported that twin boundaries strengthen nanowires regardless of their morphology that is the strength of nanowires goes up as twin spacing goes down. This article shows that twin boundaries do not always strengthen nanowires. Using classical molecular dynamics simulations the authors show that whether twin boundaries strengthen nanowires depends on the necessary stress for dislocation nucleation which in turn depends on surface morphologies. When nanowires are circular cylindrical the necessary stress of dislocation nucleation is high and the presence of twin boundaries lowers this stress twin boundaries soften nanowires. In contrast when nanowires are square cylindrical the necessary stress of dislocation nucleation is low and a higher stress is required for dislocations to penetrate twin boundaries they strengthen nanowires. Keywords Nanowire Twin Strengthening Dislocation Simulation Introduction Metallic nanowires 1 have been a focus of concerted efforts in last decade. Being sensitive to physical stimuli such as force and electricity and being capable of operating under high frequencies metallic nanowires have found applications in nanoelectromechanical systems 2 . Metallic nanowires are also useful in scanning tunneling microscope STM and atomic force microscope AFM for Y. Zhang H. Huang El Department of Mechanical Aerospace and Nuclear Engineering Rensselaer Polytechnic Institute Troy New York 12180 USA e-mail hanchen@ nanoscale tip-sample interactions 3 . Common in these applications are mechanical deformations of the nanowires which affect their functionalities. Therefore it is important to understand how nanowires respond to mechanical loading to realize their .
