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      Electron-beam-assisted superplastic shaping of nanoscale amorphous silica

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          Abstract

          At room temperature, glasses are known to be brittle and fracture upon deformation. Zheng et al. show that, by exposing amorphous silica nanostructures to a low-intensity electron beam, it is possible to achieve dramatic shape changes, including a superplastic elongation of 200% for nanowires.

          Abstract

          Glasses are usually shaped through the viscous flow of a liquid before its solidification, as practiced in glass blowing. At or near room temperature (RT), oxide glasses are known to be brittle and fracture upon any mechanical deformation for shape change. Here, we show that with moderate exposure to a low-intensity (<1.8×10 −2 A cm −2) electron beam (e-beam), dramatic shape changes can be achieved for nanoscale amorphous silica, at low temperatures and strain rates >10 −4 per second. We show not only large homogeneous plastic strains in compression for nanoparticles but also superplastic elongations >200% in tension for nanowires (NWs). We also report the first quantitative comparison of the load-displacement responses without and with the e-beam, revealing dramatic difference in the flow stress (up to four times). This e-beam-assisted superplastic deformability near RT is useful for processing amorphous silica and other conventionally-brittle materials for their applications in nanotechnology.

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          Most cited references11

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          Radiation damage in the TEM and SEM.

          We review the various ways in which an electron beam can adversely affect an organic or inorganic sample during examination in an electron microscope. The effects considered are: heating, electrostatic charging, ionization damage (radiolysis), displacement damage, sputtering and hydrocarbon contamination. In each case, strategies to minimise the damage are identified. In the light of recent experimental evidence, we re-examine two common assumptions: that the amount of radiation damage is proportional to the electron dose and is independent of beam diameter; and that the extent of the damage is proportional to the amount of energy deposited in the specimen.
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            Force fields for silicas and aluminophosphates based on ab initio calculations.

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              Fabrication of solid-state nanopores with single-nanometre precision.

              Single nanometre-sized pores (nanopores) embedded in an insulating membrane are an exciting new class of nanosensors for rapid electrical detection and characterization of biomolecules. Notable examples include alpha-hemolysin protein nanopores in lipid membranes and solid-state nanopores in Si3N4. Here we report a new technique for fabricating silicon oxide nanopores with single-nanometre precision and direct visual feedback, using state-of-the-art silicon technology and transmission electron microscopy. First, a pore of 20 nm is opened in a silicon membrane by using electron-beam lithography and anisotropic etching. After thermal oxidation, the pore can be reduced to a single-nanometre when it is exposed to a high-energy electron beam. This fluidizes the silicon oxide leading to a shrinking of the small hole due to surface tension. When the electron beam is switched off, the material quenches and retains its shape. This technique dramatically increases the level of control in the fabrication of a wide range of nanodevices.
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                Author and article information

                Journal
                Nat Commun
                Nature Communications
                Nature Publishing Group
                2041-1723
                01 June 2010
                : 1
                : 24
                Affiliations
                [1 ]simpleInstitute of Microstructure and Property of Advanced Materials, Beijing University of Technology , Beijing 100124, China.
                [2 ]simpleCenter for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University , Xi'an 710049, China.
                [3 ]simpleDepartment of Materials Science and Engineering, John Hopkins University , Baltimore, MD 21218, USA.
                [4 ]simpleHysitron Applied Research Center in China (HARCC), Xi'an Jiaotong University , Xi'an 710049, China.
                [5 ]simpleDepartment of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, PA 15261, USA.
                [6 ]simpleDepartment of Chemistry, University of California , Riverside, CA 92521, USA.
                [7 ]These authors contributed equally to this work.
                Author notes
                Article
                ncomms1021
                10.1038/ncomms1021
                3047011
                20975693
                83a06937-60ab-4a89-b503-ade3a96660a3
                Copyright © 2010, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.

                This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/

                History
                : 03 March 2010
                : 04 May 2010
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