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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

Nano technology

John Summerscales

School of Marine Science and Engineering

University of Plymouth

orders of magnitude
Orders of magnitude

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

sub metre scales
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
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
carbon
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
graphene
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/

nanotubes
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

nanotubes8
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
nanotube production
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.
nanotube purification
Nanotube purification
  • oxidation at 700°C (<5% yield)
  • filtering colloidal suspensions
  • ultrasonically assisted microfiltration
  • microwave heating together with acid treatments to remove residual metals.
nanotube properties
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
2d group iv element monolayers
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 ?
g raphene
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
curran carrot fibres
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.
exfoliated clays
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)
exfoliated clays16
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
nano technology fabrication and probes
nano-technology fabrication .. and .. probes
  • chemical vapour deposition
  • electron beam or UV lithography
  • pulsed laser deposition
  • atomic force microscope
  • scanning tunnelling microscope
  • superconducting quantum interference device (SQUID)
atomic force microscope
Atomic force microscope
  • image from http://en.wikipedia.org/wiki/Atomic_force_microscope

measures force and deflection at nanoscale

scanning tunnelling microscope
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
superconducting quantum interference device squid
Superconducting QUantum Interference Device (SQUID)
  • measures extremely weak magnetic signals
  • e.g. subtle changes in the electromagnetic energy field of the human body.
mems micro electro mechanical systems
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

controlled crystal growth
Controlled crystal growth
  • Brigid Heywood
    • Crystal Science Group at Keele
  • controlling nucleation and growthof inorganic materialsto make crystalline materials
  • protein templates
acknowledgements
Acknowledgements
  • Various websites from whichimages have been extracted
to contact me
To contact me:
  • Dr John Summerscales
  • ACMC/SMSE, Reynolds Room 008

University of Plymouth

Devon PL4 8AA

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