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Nano technology. John Summerscales School of Marine Science and Engineering University of Plymouth. Orders of magnitude. * note that capital K is used, in computing, to represent 2 10 or 1024, while k is 1000. . Sub-metre scales. 0.0532 nm = radius of 1s electron orbital

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Nano technology l.jpg

Nano technology

John Summerscales

School of Marine Science and Engineering

University of Plymouth


Orders of magnitude l.jpg

Orders of magnitude

* note that capital K is used, in computing, to represent 210 or 1024, while k is 1000.


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Sub-metre scales

0.0532 nm = radius of 1s electron orbital

0.139 nm = C-C bond length in benzene

0.517 nm = lattice constant of diamond


Nanostructures l.jpg

Nanostructures

  • surface structures with feature sizesfrom nanometres to micrometres

  • white light optics limited to ~1μm

  • use electron-beam or x-ray lithographyand chemical etching/deposition

  • image = calcium fluorideanalog of a photoresist fromhttp://mrsec.wisc.edu/seedproj1/see1high.html


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Carbon

Elemental carbon may be

  • amorphous

    or one of two crystalline forms:

  • diamond (cubic crystal sp3 structure)

  • graphite (contiguous sp2 sheets)

    • graphene (single atom thickness layers of graphite)

      or at nanoscale can combine to form

  • spheres (buckminsterfullerenes or “bucky balls”)

  • and/or nanotubes


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Graphene

single atom thickness layers of graphite

  • thinnest material known

  • one of the strongest materials known

  • conducts electricity as efficiently as copper

  • conducts heat better than all other materials

  • almost completely transparent

  • so dense that even the helium atomcannot pass through

    http://www.graphene.manchester.ac.uk/


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Nanotubes

  • Carbon-60 bucky-balls (1985)

  • graphitic sheets seamlessly wrappedto form cylinders (Sumio Iijima, 1991)

  • few nano-meters in diameter, yet (presently) up to a milli-meter long

    Image from http://www.rdg.ac.uk/~scsharip/tubes.htm


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Nanotubes

  • SWNT = single-wall nano-tube

    • benzene rings may be

      • zigzag: aligned with tube axis

      • armchair: normal to tube axis

      • chiral: angled to tube axis

    • Image fromhttp://www.omnexus.com/documents/shared/etrainings/541/pic1.jpg via

      http://www.specialchem4polymers.com/resources/etraining/register.aspx?id=541&lr=jec

  • MWNT = multi-wall nano-tube

    • concentric graphene cylinders


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Nanotube production

  • arc discharge through high purity graphite electrodes in low pressure helium (He)

  • laser vapourisation of a graphite target sealed in argon (Ar) at 1200°C.

  • electrolysis of graphite electrodes immersed in molten lithium chloride under an Ar.

  • CVD of hydrocarbonsin the presence of metals catalysts.

  • concentrating solar energy onto carbon-metal target in an inert atmosphere.


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Nanotube purification

  • oxidation at 700°C (<5% yield)

  • filtering colloidal suspensions

  • ultrasonically assisted microfiltration

  • microwave heating together with acid treatments to remove residual metals.


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Nanotube properties

  • SWNT (Yu et al)

    • E = 320-1470 (mean = 1002) GPa

    • σ´ = 13-52 (mean = 30) GPa

  • MWNT (Demczyk et al)

    • σ´ = 800-900 GPa

    • σ´ = 150 GPa


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2D group IV element monolayers

Central column of periodic table

(covalent bonding atoms)

  • graphene (2D carbon)

  • silicene (2D silicon) unstable

  • germanene (2D germanium) rare

  • stanene (2D tin)

  • plumbene (2D lead) not attempted ?


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Graphene

* in-plane bond length = 0.142 nm (vs 0.133 for C=C bond)

  • http://www.graphene.manchester.ac.uk/story/properties/

  • http://www.graphenea.com/pages/graphene-properties


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Curran®: carrot fibres

  • CelluComp (Scotland)

    • nano-fibres extracted from vegetables

    • carrot nano-fibres claimed to have:

      • modulus of 130 GPa

      • strengths up to 5 GPa

      • failure strains of over 5%

    • potential for turnips, swede and parsnips

    • first product is "Just Cast" fly-fishing rod.


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Exfoliated clays

  • layered inorganic compoundswhich can be delaminated

  • most common smectite clay used for nanocomposites is montmorillonite

    • plate structure with a thickness of one nanometre or less and an aspect ratio of 1000:1(hence a plate edge of ~ 1 μm)


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Exfoliated clays

  • Relatively low levels of clay loadingare claimed to:

    • improve modulus

    • improve flexural strength

    • increase heat distortion temperature

    • improve gas barrier properties

    • without compromising impact and clarity


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nano-technologyfabrication .. and .. probes

  • chemical vapour deposition

  • electron beam or UV lithography

  • pulsed laser deposition

  • atomic force microscope

  • scanning tunnelling microscope

  • superconducting quantum interference device (SQUID)


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Atomic force microscope

  • image from http://en.wikipedia.org/wiki/Atomic_force_microscope

measures force and deflection at nanoscale


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Scanning tunnelling microscope

  • scans an electrical probe over a surface to detect a weak electric currentflowing between the tip and the surface

  • image fromhttp://nobelprize.org/educational_games/physics/microscopes/scanning/index.html


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Superconducting QUantum Interference Device (SQUID)

  • measures extremely weak magnetic signals

  • e.g. subtle changes in the electromagnetic energy field of the human body.


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MEMS: micro electro mechanical systems

  • Microelectronics and micromachiningon a silicon substrate

  • MEMS electrically-driven motors smaller than the diameter of a human hair

    Image from http://www.memsnet.org/mems/what-is.html


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Controlled crystal growth

  • Brigid Heywood

    • Crystal Science Group at Keele

  • controlling nucleation and growthof inorganic materialsto make crystalline materials

  • protein templates


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Acknowledgements

  • Various websites from whichimages have been extracted


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To contact me:

  • Dr John Summerscales

  • ACMC/SMSE, Reynolds Room 008

    University of Plymouth

    Devon PL4 8AA

  • 01752.23.2650

  • 01752.23.2638

  • [email protected]

  • http://www.plym.ac.uk/staff/jsummerscales


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