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Nano technology

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

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  1. Nano technology John Summerscales School of Marine Science and Engineering University of Plymouth

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

  3. 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

  4. 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

  5. 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

  6. 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/

  7. 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

  8. 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

  9. 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.

  10. Nanotube purification • oxidation at 700°C (<5% yield) • filtering colloidal suspensions • ultrasonically assisted microfiltration • microwave heating together with acid treatments to remove residual metals.

  11. 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

  12. 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 ?

  13. 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

  14. 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.

  15. 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)

  16. 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

  17. 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)

  18. Atomic force microscope • image from http://en.wikipedia.org/wiki/Atomic_force_microscope measures force and deflection at nanoscale

  19. 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

  20. Superconducting QUantum Interference Device (SQUID) • measures extremely weak magnetic signals • e.g. subtle changes in the electromagnetic energy field of the human body.

  21. 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

  22. Controlled crystal growth • Brigid Heywood • Crystal Science Group at Keele • controlling nucleation and growthof inorganic materialsto make crystalline materials • protein templates

  23. Acknowledgements • Various websites from whichimages have been extracted

  24. To contact me: • Dr John Summerscales • ACMC/SMSE, Reynolds Room 008 University of Plymouth Devon PL4 8AA • 01752.23.2650 • 01752.23.2638 • jsummerscales@plymouth.ac.uk • http://www.plym.ac.uk/staff/jsummerscales

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