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1.11.2.2._GRAPHITE_AND_GRAPHENE

[ ‘Graphene: Status and Prospects’, A.K. Gelen, Science, Vol 324, 19 th June 2009, 1530-1534;

‘Carbon Woderland’, Andre K. Geim and Philby Kim, Scientific American, April 2008, 90-97]

The two other alltropic forms of Carbon are Graphite and Buckminsterfullerene[Appendix XXXXV]. The crystal structure of these two allotropes are shown in Figure 1.57. The comparative study of these three alltropic forms of carbon is shown in Table 1.22.

In Graphite each layer has hexagonal arrangement of carbon atoms. As seen in Figure 1.57, each carbon atom has three neighbouring carbon atoms covalently bonded. This arrangement leaves 1 electron unbounded hence free to be released through out the lattice. This makes Graphite a good conductor and it has a metallic luster. There is a weak Van der Waals induced bonding between the layers as already discussed in Bonding chapter. Hence layers can move past one another and flak easily. They find applications in lubricants and pencil lead.

Graphite is a 3D bulk material which consists of stacks of 2D one atom hexagonal rings of Carbon sheets. In recent years with the advent of nanotechnology , it has been possible to separate out individual sheets and experiment with it. The flat sheet of hexagonal rings of Carbon is known as GRAPHENE. Wrapped up graphene is known as fullerenes. When it is wrapped up in honey comb cylinder like structure it is called carbon nano-tubes and when it is wrapped as soccer ball shaped as in Figure 1.57 then it is called bucky ball.

This 1 atom thick 2D grapheme is a wonder material. It is the strongest material- stronger than steel. The orderly arrangement of hexagonal rings is repeated through out the sheet with remarkable regularity as a result even at room temperature of 300K electron’s mean free path is in micrometer. This implies very few and far between scattering. Hence under the influence of electric field, electrons behave like mass-less Dirac quasi-particles on which relativistic quantum mechanics or Quantum Electrodynamics applies. Electron travels at (1/300) of speed of light. This is in contrast to electrons in 3D semiconductor where mass is near that in free space and mobility and drift velocity is much lower. These useful properties has opened immense possibilities for grapheme based electronics. Ballistic FETs are emerging which are suitable for 100GHz and above application. Graphene has given a new lease of life to Moore’s Law of microminiaturization. It will enable the scaling down right up to 10 nm.

Under normal conditions graphite crystallizes out but under excessive pressure condition diamond is favoured. Once the diamond has crystallized it remains stable under normal temperature and pressure. Deep in Earth’s vegetation remains are transformed into diamonds and coal over eons. This is the source of natural diamond.

Synthetic diamond can be obtained in the following manner. Graphite is dissolved in molten cobalt or nickel and the mixture is compressed by 60,000 bar pressure at 1600K. Less than 1 mm wide diamonds can be synthesized in this way. It is widely used in industrial applications for cutting and grinding tools.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
how to synthesize TiO2 nanoparticles by chemical methods
Zubear
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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