Transcript Training - Plymouth University

Nano technology
John Summerscales
School of Marine Science and Engineering
University of Plymouth
Orders of magnitude
x
10-x
10+x
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.
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
Nanostructures

surface structures with feature sizes
from nanometres to micrometres
white light optics limited to ~1μm
 use electron-beam or x-ray lithography
and chemical etching/deposition


image = calcium fluoride
analog of a photoresist from
http://mrsec.wisc.edu/seedproj1/see1high.html
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
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 atom
cannot pass through
http://www.graphene.manchester.ac.uk/
Graphene
Property
Units
Magnitude
Thickness
nm
0.33*
μg/m2
770
Tensile modulus
GPa
500
Tensile strength
GPa
1000
%
absorption
2.3
Areal density
Transparency
*
1.
2.
Comment
Source
[1]
~1g / football field
[2]
[2]
~333x virgin CF
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
[1]
[1]
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.sapp.pdf
Nanotubes
Carbon-60 bucky-balls (1985)
 graphitic sheets seamlessly wrapped
to 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
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/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
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 hydrocarbons
in the presence of metals catalysts.
 concentrating solar energy onto
carbon-metal target in an inert atmosphere.

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

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
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 ?
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
layered inorganic compounds
which 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 clays

Relatively low levels of clay loading
are 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
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
measures force
and deflection
at nanoscale

image from http://en.wikipedia.org/wiki/Atomic_force_microscope
Scanning tunnelling microscope

scans an electrical probe over a surface
to detect a weak electric current
flowing between the tip and the surface

image from
http://nobelprize.org/educational_games/physics/microscopes/scanning/index.html
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

Microelectronics
and micromachining
on 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

Brigid Heywood
• Crystal Science Group at Keele

controlling nucleation and growth
of inorganic materials
to make crystalline materials

protein templates
Acknowledgements

Various websites from which
images have been extracted
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