university of maryland mechanical engineering department structures ‘at the bottom’: carbon...
Post on 15-Jan-2016
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![Page 1: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/1.jpg)
Mechanical Engineering Department
University of Maryland
Structures ‘at the bottom’:Carbon nanotubes (CNT)• few nm diameter•10-100 m length(avg human hair is 70 m wide)
•already available commercially (5 manufacturers)•Already being applied in commercial products
![Page 2: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/2.jpg)
Mechanical Engineering Department
University of Maryland
How do we Arrange Stuff into this ‘Space at the Bottom’ ?(Nanoscale Fabrication: Molecular Manipulation)
• Machine-phase synthesis• AFM, MFM, STM, nanotweezers• Self-assembly (e.g., DNA moletronics)• Atomic layer epitaxyAFM
Tips
AFMTips
CNT
CNT Probe
Si Substrate
![Page 3: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/3.jpg)
Mechanical Engineering Department
University of Maryland
Carbon nanotube shaft with benzene ring gears [Jie Han et al]• max rpm in vacuum w/o slipping: 50-100 GHz• fabrication is done by STM (IBM has recently used STM to move organic
molecules 1.5 nm dia, consisting of 173 atoms)• molecular dynamics simulation shows
chatter/chaos
![Page 4: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/4.jpg)
Mechanical Engineering Department
University of Maryland
MEMS gear trains have been driven upto 250,000 RPM
Comparison with Larger Scales: MEMS
![Page 5: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/5.jpg)
Mechanical Engineering Department
University of Maryland
SWNT Twisting
SWNT Axial Comp.
SWNT Bending
MWNT Bending
Molecular Simulations of CNT Deformation
![Page 6: University of Maryland Mechanical Engineering Department Structures ‘at the bottom’: Carbon nanotubes (CNT) few nm diameter 10-100 m length (avg human](https://reader036.vdocument.in/reader036/viewer/2022062322/56649d4b5503460f94a28f3d/html5/thumbnails/6.jpg)
Mechanical Engineering Department
University of Maryland
Molecular models based onInteratomic Potential Functions:• Morse• Born-Oppenheimer• Lennard-Jones• Tersoff-Brenner
• Costly and Size-limited: requires simultaneous integration of 6N DEs; limited to ~105 atoms today
• Dynamic inaccuracies (wrong nonlinear behavior)
• Difficult to address nonlinearities
• Difficult to address realistic boundary conditions
• Continuum models miss some molecular conformations
Molecular Models