title: Mechanical properties of Si nanowires as revealed by in situ transmission electron microscopy and molecular dynamics simulations.
abstract: Deformation and fracture mechanisms of ultrathin Si nanowires (NWs), with diameters of down to ~9 nm, under uniaxial tension and bending were investigated by using in situ transmission electron microscopy and molecular dynamics simulations. It was revealed that the mechanical behavior of Si NWs had been closely related to the wire diameter, loading conditions, and stress states. Under tension, Si NWs deformed elastically until abrupt brittle fracture. The tensile strength showed a clear size dependence, and the greatest strength was up to 11.3 GPa. In contrast, under bending, the Si NWs demonstrated considerable plasticity. Under a bending strain of <14%, they could repeatedly be bent without cracking along with a crystalline-to-amorphous phase transition. Under a larger strain of >20%, the cracks nucleated on the tensed side and propagated from the wire surface, whereas on the compressed side a plastic deformation took place because of dislocation activities and an amorphous transition.
authors.affiliation: International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044 Japan.
authors.forename: Dai-Ming
authors.initials: DM
authors.lastname: Tang
authors.forename: Cui-Lan
authors.initials: CL
authors.lastname: Ren
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Wang
authors.forename: Xianlong
authors.initials: X
authors.lastname: Wei
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kawamoto
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Bando
authors.forename: Masanori
authors.initials: M
authors.lastname: Mitome
authors.forename: Naoki
authors.initials: N
authors.lastname: Fukata
authors.forename: Dmitri
authors.initials: D
authors.lastname: Golberg