Nano technology

1
Nano technology

• John Summerscales
• School of Marine Science and Engineering
• University of Plymouth

2
Orders of magnitude
x 10-x 10x
3 milli- (m) kilo- (k)
6 micro- (µ) mega- (M)
9 nano- (n) giga- (G)
12 pico- (p) tera- (T)
15 femto- (f) peta- (P)
18 atto- (a) exa- (E)

• 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
atto- femto- pico- nano- micro- milli- metre
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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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Graphene
Property Units Magnitude Comment Source
Thickness nm 0.33 1
Areal density µg/m2 770 1g / football field 2
Tensile modulus GPa 500 2
Tensile strength GPa 1000 333x virgin CF 1
Transparency absorption 2.3 1

• in-plane bond length 0.142 nm (vs 0.133
  for CC bond)
• http//www.graphene.manchester.ac.uk/story/propert
  ies/
• http//www.graphenea.com/pages/graphene-properties

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Penta-graphene

• announced Feb. 2015
• stable to 1000K (727ºC)
• semiconductor
• auxetic

image from http//www.pnas.org/content/suppl/2015/
01/27/1416591112.DCSupplemental/pnas.1416591112.sa
pp.pdf
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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.ht
  m

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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 from http//www.omnexus.com/documents/share
  d/etrainings/541/pic1.jpg via
• http//www.specialchem4polymers.com/resources/etra
  ining/register.aspx?id541lrjec
• 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 1200C.
• 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 700C (lt5 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
• s 13-52 (mean 30) GPa
• MWNT (Demczyk et al)
• s 800-900 GPa
• s 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) early days
• Other 2D monolayers
• borophene (2D boron / Group III)
• boron nitride (BN / Groups III/V)

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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
  10001(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

18
Electrospinning

• characteristics of both
• electrospraying, and
• conventional solution dry spinning of fibers
• electrical charge drawsvery fine (typically µm
  or nm) fibresfrom a liquid.
• image from https//en.wikipedia.org/wiki/Electrosp
  inning

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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)

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Atomic force microscope
measures force and deflection at nanoscale

• image from http//en.wikipedia.org/wiki/Atomic_for
  ce_microscope

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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.htm
  l

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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
• 01752.5.86150
• 01752.5.86101
• jsummerscales_at_plymouth.ac.uk
• http//www.plymouth.ac.uk/staff/jsummerscales