mechanics of individual nanostructures (an...

Northwestern University Rod Ruoff Nanotechnology

Mechanics of Individual Nanostructures (an overview)


Outline

1. Introduction

2. Tensile Test

3. Resonance Test

4. Other methods


Part One:

Introduction


1-D NanostructuresIn recent years various one-dimensional (1-D) nanostructures have been synthesized. A full understanding of their mechanical properties is important for applications of these novel materials.

(a) Scanning Electron Microscope (SEM) image of crystalline boron nanowires on alumina substrate

(a)(b)

(b) Transmission Electron Microscope (TEM) image of a crystalline boron nanowire


1-D Nanostructures (con’t)

TEM image of a multi-wall carbon nanotube

SEM image of arc-grown MWCNTs from MER Corp. AZ.

Single-wall carbon nanotube (SWCNT) Multi-wall carbon nanotube (MWCNT)

http://physicsweb.org/articles/world/11/1/9/1/world-11-1-9-1


Part Two:

Nanoscale Tensile Test


Tensile stretching of individual MWCNTWe will continue to study the mechanical properties for MWCNTs with our nano-manipulator.

Yu MF, Lourie O, Dyer MJ, Moloni K, Kelly TF, and Ruoff RS, Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load, SCIENCE, 287, 637-640 (2000).

Mechanical tensile testing schematic SEM images of tensile test


Tensile Test on PEO Nanofiber

E.P.S. Tan, C.N. Goh, C.H. Sow, and C.T. Lim, Tensile Test of a Single Nanofiber Using an Atomic Force Microscope Tip. Appl. Phys. Lett., 2005.86(6).

Schematic diagram of the tensile test of the nanofiber using a piezoresistive AFM tip.

A single electrospun polyethylene oxide (PEO) nanofiber is stretched with AFM cantilever tip with a micromanipulator.


Result

(left) single fiber manipulation

(top) tensile test result

E.P.S. Tan, C.N. Goh, C.H. Sow, and C.T. Lim, Tensile Test of a Single Nanofiber Using an Atomic Force Microscope Tip. Appl. Phys. Lett., 2005.86(6).


(a) The same nanocoil is clamped between two AFM cantilevers. The left cantilever is stiffer than the right cantilever. (b) the relaxed nanocoil. (c) the nanocoil at a relative elongation of 20 %. (d) the nanocoil at a relative elongation of 33 %.


Boron Nanowire: Tensile TestIndividual crystalline boron nanowire was tensile loaded with two AFM cantilevers inside SEM.


MWCNT: Sword-in-sheath FractureMulti-wall carbon nanotubes fracture in a “sword-in-sheath” manner during tensile test. Outer shellInner shells

Inner shells

outer shell

SEM images of sword-in-sheath fracture of a MWCNT under tension



Part Three:

Nanoscale Resonance Test


Mechanical Resonance: Carbon Nanotube

Poncharal,P., et al, Science, 283, 1513-1516 (1999)

(top) Elastic properties of nanotubes

(left) Electromechanical vibration of a MWCNT (A) thermal vibration (B) Fundamental resonance (C) First overtone resonance


Mechanical Resonance: DLC Pillar

Fujita,J. et al, J.Vac.Sci.Technol. B 19(6), 2834-2836 (2001)

SEM image of the vibration Schematic of mechanical vibration experimental setup


Mechanical Resonance: ZnO Nanobelt

Bai et al, App. Phys. Lett. 82(26) 4806-4808 (2003)


Mechanical Resonance: ZnO nanobelt (con’t)


SiO2 Nanowire: Source

Ultrasonically dispersed SiO2nanowire

Synthesized by Z.W. Pan (J.Am.Chem.Soc.’02)

TEM image (inserts: High resolution image and diffraction pattern)


SiO2 Nanowire: Mechanical Resonance

Electrical Excitation Mechanical Excitation

W wireW wire

W wire (counter electrode)

D. A. Dikin, X. Chen, W. Ding, G. Wagner, R. S. Ruoff, Resonance vibration of amorphous SiO2 nanowires driven by mechanical or electrical field excitation, Journal of Applied Physics 93, 226 (2003).


Quartz Fibers

Typical sample geometry: diameter: 30-100 µm, length: 5-10 mm

Quartz fibers were home-made by pulling a fused quartz rod (GE Quartz, Inc) on a wide flame.

X. Chen, S. Zhang, G.J. Wagner, W. Ding, and R. S. Ruoff, Mechanical resonance of quartz microfibers and boundary condition effects, Journal of Applied Physics, 95 (9), 4823-4828, 2003


Quartz Fiber: Mechanically Induced Resonance

Optical microscope pictures of the first four modes of resonance of a quartz microfiber. The insets are the theoretical displacement curves.


Boron Nanowire: Source

SEM image of boron nanowires on alumina substrate TEM image of a boron nanowire

Otten et al, J.Am. Chem. Soc.,124 (17), 2002


Boron Nanowire: Resonance

First two modes of resonance of a cantilevered BNW

Typical frequency response of the 1st

mode resonance

W. Ding, L. Calabri, X. Chen, K. Kohlhaas, R.S. Ruoff, Mechanics of Crystalline Boron Nanowires, manuscript in preparation


Part Four:

Other Methods


MWCNTs were pinned at one end to molyneenum disulfide surface. AFM tip was used to bend the nanotube. The bending force was measured versus displacements along the unpinned length.

Eric E. Wong et al, Nanobeams Mechanics: Elasticity, Strength,asnd Toughness of Nanorods and Nanotubes, Science, Vol 277,1997

Elasticity, Strength, and Toughness of Nanobeam


Con’t

Images of a 4.4-nm-diameter MWNT before and after bending on an oxidized silicon substrate

Calculation model used to determine the mechanical property of MWNTs.

Schematic of a pinned beam with a free end. The beam of length L is subjected to a point load P at x = aand to a distributed friction force f.

Eric E. Wong et al, Nanobeams Mechanics: Elasticity, Strength,asnd Toughness of Nanorods and Nanotubes, Science, Vol 277,1997


AFM Three-point Bend Test

E.P.S. Tan and C.T. Lim, Physical properties of a single polymeric nanofiber.Appl. Phys. Lett., 2004. 84(9): 1603-1605.


Nanoindentation of Nanowire

Li, XD, Gao, HS, Murphy, C.J, Caswell, K.K, Nanoindentation of Silver Nanowires, Nano Letter, 2003, 3(11) 1495-1498

AFM image of a nanowire AFM image of indents on a nanowire

Hardness and elastic modulus of a silver nanowire were directly measured with a nanoindenter.


M. F. Yu, B. I. Yakobson and R. S. Ruoff, Controlled sliding and pullout of nested shells in individual multiwalled carbon nanotubes, J. Phys. Chem., B, 104, 8764-8767 (2000).

Controlled Sliding and Pullout


Low-Friction Nanoscale Bearing from MWCNT

Schematic Representation:

A. A MWCNT mounted on stage.

B. Open the end of the MWCNT.

C. Attach the nanomanipulator to the core tube.

D. The core tube was repeatedly telescoped and observe wear.

E. The core was released and pulled back into outside-shell by van de Waals force.

John Cumings et al ,Low-Friction Nanoscale Liner Bearing Realized from MECNT, Science, Vol 289, July 2000


The repeat extension and retraction of nanotube segments revealed no wear or fatigue on atomic scale.

It’s possible to construct wear-free surfaces by nanotubes

(left top)TEM image of a telescoped nanotube

(left bottom) TEM image of a bamboo section of a MWCNT.The core tubes on the right was telescoped outward.

Con’t

John Cumings et al ,Low-Friction Nanoscale Liner Bearing Realized from MECNT, Science, Vol 289, July 2000


Poncharal et al, Electrostatic Deflections and Electromechanical Resonances of Carbon nanotubes, Science, Vol 283, 1999

(a) Uncharged Nanotube

(b) Charged nanotube.

Electromechanical Resonance of MWCNT

Electrostatic potential field was used to deflected the carbon nanotube.The measured deflection ofnanotube was proportional to the square of static potential.


Schematic Illustration of the Project

Fixed end

Actuator—the moving component, integrated with force sensor

10-10 SWCNT, MWCNT, nanowire, or other nanomaterials

direct imaging to measure ∆∆∆∆x

Anchor

Anchor

Electrode

Electrode

fixed

Side view of the design

Handling layer—Si or Pyrex glass

Anchor, dielectric material—SiO2

Electrodes Actuating and sensing components

Shaoning Lu*


Thermally Actuated Testing Stage

Device ready to test

Si device

Carbon tape

Copper electrodes

Connection to power source

Shaoning Lu, Dmitry Dikin,Junghoon Lee, Rodney S. Ruoff, Rev. of Sci. Instruments, accepted

mechanics of individual nanostructures (an...

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