摘要：Compared with the inherent brittleness of bulk silicon(Si)at ambient temperature,the nanosized Si materials with very high strength,plasticity,and anelasticity due to size effect,are all ***,the ultimate stretchability of Si nanostructure has not yet been demonstrated due to the difficulties in experimental ***,directly performing in-situ tensile tests in a scanning electron microscope after developing a protocol for sample transfer,shaping and straining,we report the customized nanosized Si mechanical metamaterial which overcomes brittle limitations and achieves an ultra-large tensile strain of up to 95%using the maskless focused ion beam(FIB)*** unprecedented characteristic is achieved synergistically through FIB-induced size-softening effect and engineering modification of mechanical metamaterials,revealed through analyses of finite element analysis,atomic-scale transmission electron microscope characterization and molecular dynamics *** work is not only instructive for tailoring the strength and deformation behavior of nanosized Si mechanical metamaterials or other bulk materials,but also of practical relevance to the application of Si nanomaterials in nanoelectromechanical system and nanoscale strain engineering.

摘要：Oxidative etching can be a powerful approach to modify the morphology of nanoscale materials for various *** of the etching mechanisms and morphological evolution during etching is *** the liquid cell transmission electron microscopy,we investigate the etching behavior of gold nanorods under different electron beam dose rates:caseⅠ,3.5×10^9 Gy s^-1;caseⅡ,1.5×10^10 Gy s^-1;caseⅢ,4.5×10^10 Gy s^-*** Au nanorod develops facets at the tips(caseⅠ)or adopts a transit ellipsoid shape and eventually dissolves(caseⅡ),depending on the dose *** rapid etching under an even higher dose rate(caseⅢ)may lead to the formation of Au3+ion-rich intermediates around the nanorod,which further accelerates the lateral etching and unexpectedly increases the aspect ratio of the *** quantitative analysis shows that the critical size of the nanorod,below which the etching rate increases significantly with the reduction of nanorod size,may vary subject to the degree that the system is away from *** results provide significant insights into the oxidative etching mechanisms and shed light on the rational design and synthesis of nanostructures.