Nano technologyNano technology

John SummerscalesSchool of Marine Science and Engineering

University of Plymouth

Orders of magnitudeOrders of magnitude

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

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)

Sub-metre scalesSub-metre scales

atto- femto- pico- nano- micro- milli- metre

0.0532 nm = radius of 1s electron orbital

0.139 nm = C-C bond length in benzene

0.517 nm = lattice constant of diamond

NanostructuresNanostructures 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 fromhttp://mrsec.wisc.edu/seedproj1/see1high.html

CarbonCarbonElemental 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

GrapheneGraphene

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/

GrapheneGraphene

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 C=C bond)

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

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

Penta-graphenePenta-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

NanotubesNanotubes

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

NanotubesNanotubes 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 productionNanotube 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 purificationNanotube purification

oxidation at 700°C (<5% yield) filtering colloidal suspensions ultrasonically assisted microfiltration microwave heating together with acid

treatments to remove residual metals.

Nanotube propertiesNanotube 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 monolayers2D group IV element monolayers

Central column of periodic table

(covalent bonding atoms)graphene (2D carbon)silicene (2D silicon) unstablegermanene (2D germanium) rarestanene (2D tin)plumbene (2D lead) not attempted ?

CurranCurran®®: carrot fibres: 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 claysExfoliated 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 claysExfoliated 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-technologynano-technologyfabrication .. and .. probesfabrication .. 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 microscopeAtomic force microscope

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

measures force and deflection at nanoscale

Scanning tunnelling microscopeScanning 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 Superconducting QUantum Interference Device (SQUID)Interference Device (SQUID)

measures extremely weak magnetic signals e.g. subtle changes in the electromagnetic

energy field of the human body.

MEMS: micro electro MEMS: micro electro mechanical systemsmechanical 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 growthControlled crystal growth

Brigid Heywood• Crystal Science Group at Keele

controlling nucleation and growthof inorganic materialsto make crystalline materials

protein templates

AcknowledgementsAcknowledgements

Various websites from whichimages have been extracted

To contact me:To contact me: Dr John SummerscalesACMC/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