Graphene The most awaited material in history

1. Graphene
The most awaited material in history
M. Zubair Ahmed
Dept. of Mechanical
Guru Nanak Institutions Technical Campus
Hyderabad
zubairwajid@ymail.com
+91 8008418347
Mohit Gidwani
Dept. of Mechanical
Guru Nanak Institutions Technical Campus
Hyderabad
mohitgidwani08@yahoo.com
+91 9849188041
Abstract—The material so close yet so far. The paper intent
to bring the graphene into the lime light. A brief history of the
material has been discussed. Graphene, a layer of graphite just
one atom thick, isn't called a wonder material for nothing. It
has introduces some of the basic distinguishing properties of
this wonder material along with various most promising and
potential future application.
Index Terms—Exfoliation, Epitaxial, photo luminescence,
Quasistatic particles.
I. INTRODUCTION
With its superlative properties, Graphene tends to enjoy
the privilege of being the most researched material in the
world. Despite of its short history, hundreds of research
paper rolls out from time to time starting a new trend in area
of condensed matter physics and its application. The thinnest
ever known and the strongest ever measured. The Material
first of its kind. Its unbound applications are soon to be
realized and revealed.
II. HISTORY
The essence of graphite has been felt as early as x
ray diffraction technique has been discovery. Since
then from 1859 search for graphene has begun. V.
Kohischutter and P. Haenni in 1918, described the
properties of graphite oxide .It was first studied as a
limiting case of Graphite by Phillip Wallace as long as
1947.The earliest Tunnel Electron Microscope images
(TEM) of few layer graphene were published by
G.Ruess and F. Vogt in 1948.In the same year it was
pointed out that current carriers were effectively
massless by Gordon Walter, David P. Devincenzo and
Eugene J Mele. In 1859 Benjamin Collins Brodie was
aware of highly lamellar structure of thermally reduced
graphite oxide. The term first appeared in year 1984
when co-workers along with S. Mouras described the
graphite layers which has various compounds inserted
between them forming Graphite Intercallation
Compounds. They joined the word Graphite + benzene,
= Graphene, benzene because of its resemblance with
Graphene’s bonding. Attempts to grow graphene on
single crystal surface have been in process since
1970’s,but strong interactions with surface always
adhered the growth of graphene.It was not until 2004,
that gold rush of graphene started with the discovery of
stable graphene flakes.
III. DISCOVERY
Prior to 2002, it was believed that graphene would
be unstable in its free form and also much about its
properties was unmeasured. In late 2002, Andre Geim,
a Russian physicists working at University of
Manchester, intrigued how far a piece of graphite can
go thin. He began polishing down the material into thin
slices. This however didn’t lead to any sufficiently thin
slices. Kostya Novoselov, a Russian physicists working
at University of Manchester at other project that time.
It was then suggested by Oleg Shklyareevskii, a senior
fellow from Kharkov, Ukraine that the material thrown
on the tape, which was used for cleaning graphite has
thinner layers than that by polishing down by Andre.
Later Kostya and Andre came together to investigate
the graphite flakes on the tape and to look how thin a
flake would be made. In 2003 they first succeeded in
preparing the first isolated graphene flake and this was
published in 2004. For which they won Nobel Prize in
2010. With the inspiration there was no stopping in the
inquisitive research all around the world for graphene.
Many scientists and pro doctorates were sent to Britain
to learn the technique of isolation of graphene.
IV. ISOLATION
Few of the technique are presented for the isolation
of graphene sheet, though current research is in
progress to find more economical and convenient
method.

2. Graphite Oxide Reduction1.
It was probably the historically first method of
graphene synthesis. The first literature was compiled
by P. Boehm, by reducing monolayer of graphene
oxide to graphene. This report was formed by him in
1962, for which recently he was awarded Nobel Prize.
This method involves washing graphite in H2SO4 and
K2S2O8 and oxidizing the graphite with KMnO4 and
H2SO4
Afterwards, the graphite goes through ultrasonic
cleaning before the samples are exfoliated. Then the
graphite samples are centrifuged and neutralized. The
result of this is an extremely
Hydrophilic graphene oxide. Although this process
damages graphene’s electronic properties, the chemical
reduction of graphene oxide plays a crucial role in
graphene synthesis. By performing another process
involving graphene’s pi bond interactions and a
reducing agent, graphene can return to its original state,
maintaining its conductivity, flatness, and
transparency; however, the finished product will not be
the same as pristine graphene and will contain a few
flaws.
Applying a layer of graphite oxide to a DVD disk
and burned in a DVD writer resulted in a thin graphene
films.
Exfoliation Method2.
The most famous method in history of graphene,
with the reward for being the first successful isolation
of graphene. Also drawing method or Scotch Tape
Method. Discovered by Manchester group. Obtained
by micro- mechanical alleviation of graphite. Elevation
was obtained by adhesive tape to repeatedly split
graphite crystals into increasingly thinner pieces[1].
The process achieves a thickness of 254 millionth of a
millimeter. When transparent tape is used the flakes are
dissolved in acetone, then sediment on silicon wafer.
Superficially, the technique looks as nothing more
sophisticated than drawing by a piece of graphite
Individual atomic planes are then hunted in an optical
microscope. Although time consuming and delicate it
remains the favorite method for basic of research. The
latest in the category is avoiding dry decomposition.
The sheets up to an mm length have been isolated so
far. It yet remains most vague technique not suitable
for mass production.
Chemical vapor deposition3.
It is used to produce high-quality, large area single
and multi-layered graphene. The process begins by
dissolving carbon onto silicon or other transition metal
substrate and placing the substrate in a chamber with
high vacuum conditions [2]. The chamber is
maintained at a temperature around 1000 degrees
Celsius, and is filled with a mixture of H2 and Argon
gas to remove traces of organic materials and oxide
layers from the substrate. Then the substrate is heated
for one hour under ambient pressure and then cooled to
room temperature using a flowing gas mixture of CH4
and H2 [2]. The purpose of chemical vapor deposition
is to integrate a spread of carbon atoms onto the
substrate’s surface.
Epitaxial Growth4.
Another method of obtaining graphene is to heat
silicon carbide (SiC) to high temperatures (>1,100 °C)
under low pressures (~1333.2 Pa) to reduce it to
graphene.[3] This process produces epitaxial graphene
with dimensions dependent upon the size of the SiC
substrate (wafer). The face of the SiC used for
graphene formation, silicon- or carbon-terminated,
highly influences the thickness, mobility and carrier
density of the graphene.
Many important graphene properties have been
identified in graphene produced by this method.
Epitaxial graphene on SiC can be patterned using
standard microelectronics methods. The possibility of
large integrated electronics on SiC-epitaxial graphene
was first proposed in 2004 [4].
Ultrasonic Cleavage5.
Mechanical cleavage can be done automatic by
process of employing ultrasonic cleavage. This leads to
a stable micro suspension of submicron graphene
crystal, which can be then loosened graphite, in which
atomic planes are partially detached first by
intercalation, making the sonification more efficient.
This may be mass production method of graphene of
the future.

3. V. ATOMIC STRUCTURE
Fig 1. Structure of Graphene
Graphene is a substance composed of pure carbon,
with atoms arranged in regular hexagon pattern similar
to graphite, but in one atom thick sheet. It is very
closely packed. Its structure is a single planar sheet of
sp2
bonded carbon atoms, densely packed. The first 2
dimensional crystal materials discovered it belongs to
carbon allotrope family. After its discovery scientist
have access to materials of all dimensionalities, include
quantum dot (0D), nanowires (1D), itself (2D) and
graphite (3D).
The structure was studied by Tunnel Electron
Microscope. The diffraction resulted in expected
honeycomb structure. The carbon-carbon bond length
is about 0.142 nanometers. Graphene sheets are most
easily visualized as an atomic scale chicken wire made
of carbon atoms and their bonds. It is the single layer of
graphite. It is seen that graphene can repair holes on its
sheet when exposed or bombarded by pure carbon
atoms [5]. Graphene’s structure can be interpreted as
either ―arm chair‖ or ―zig-zag,‖ depending on how the
graphene sheet is oriented.
Fig 2. Orientations of Graphene
VI. 2-D CRYSTAL
It was hypothesized that graphene should not be able
to exist without being destroyed by thermal fluctuation
as stated by some old articles. These fluctuations
should cause the 2D crystal to melt. Also that it would
roll or scroll and buckle when spread out. This was
believed because it was seemed again nature for
growth of a 2D crystal. As crystal implies high
temperature and therefore thermal fluctuations are
detrimental for stability, and the adjacent thermal
vibrations in crystals grows rapidly forcing 2D
crystallites to morph into a variety of stable 3D
crystallites. Impossibility of growing 2D crystal
doesn’t hinder in from obtaining a 2D crystal from
other techniques as included. Indeed growing a
monolayer on top of other crystal and then removing
2D crystal at low temperature such that thermal
fluctuations are minimal unable to break the bond and
mold them into 3D shapes.
Not only graphene a 2-D crystal has been obtained this
way, atomic planes of Boron Nitride, Mica and
complex oxides were obtained by drawing method.
VII. MECHANICAL PROPERTIES
Graphene appears to be one of the strongest
materials ever tested [6]. Measurements have shown
that graphene has a breaking strength over 100 times
greater than a hypothetical steel film of the same
(incredibly thin) thickness,[7] with a tensile modulus
(stiffness) of 1 TPa whereas steel’s is 0.18 TPa. Four
time more stronger than diamond.
The strength comes with strong atomic between
carbon- carbon atoms, and with the fact that there is no
grain boundary. As an addendum, materials are not the
same as macrostructure. A regular graphite-plate
analogy falls apart because an actual, tangible bit of
graphite is made up of lots of microscopic graphite
grains, each with a different orientation. If by some
miracle of chaos and randomness, each grain had
aligned up perfectly, then your graphite would indeed
be unbreakable along two of its three axes. However,
real life doesn't work like that - when stress is applied
to a piece of graphite, it's the planes closest to
perpendicular to the stress direction that will fracture
first. This will then increase the stress on other grains
that are oriented in 'breakable' way, and eventually the
whole lot gives up. But this convection fails in
graphene as there are continuous pure single layer of
regular sheet of atoms without grain boundaries.
Material Scientist at Brown University are now able
to stich individual graphene sheets together to create
sheets enough for possible investigation. The formed
grain boundary doesn’t in fact compromise on the
strength of sheet comparable with pure continuous
sheet. The fact lies with angle with which they are

4. stitched. When they are stitched some of carbon forms
seven carbon bonds – Heptagons which are observed to
be stronger than six bonded carbon. The optimal angle
of 28.7 degrees for sheets with an armchair pattern and
21.7 degrees for sheets with a zigzag layout were taken
to exact for non-reduction of strength. These are called
large-angle grain boundaries.
It also very light weight, weighing about
0.77 mg / m2
. The Nobel announcement illustrated that
by 1 sq.m of graphene sheet supporting a 4 kg cat
would weight only as much as one of the cats whiskers.
VIII. THERMAL PROPERTIES
At near room temperature, graphene’s thermal
conductivity was measured to be between
4840 – 5300 W/m.K. These measurements were made
by non-contact optical technique. The values obtained
are more than that of carbon nanotubes and diamond
(1200 W/m.K). It can be shown that from
Wiedermann-Franz law thermal conductivity is photon
dominated. The thermal conductivity is dependent on
T2
.It shows membrane effect.
IX. OPTICAL PROPERTIES
Graphene also portrays extraordinary optical
properties. Graphene only has 2.3% cloudiness on its
honeycomb surface. This leaves an over 98% visual
transmission rate, which makes graphene almost
completely transparent [8]. To make graphene even
more transparent, scientists use a method called
electrical gating, which is made possible by the limit
of electrons in the monolayer and the low density of
states near a Dirac point. Graphene also displays
remarkable photoluminescence, which is quantum-
mechanical light emission.
Graphene’s photoluminescence abilities are
demonstrated first by using chemical or physical
methods to weaken the connection of the pi-electron
network [8].
X. ELECTRICAL PROPERTIES
The most explored aspect of graphene physics is its
electronic properties. From the most general
perspective, several features make Graphene electronic
properties truly unique and different from those of any
other known condensed matter system.
The first and most discussed is of course graphene,
is its electronic spectrum. Electron waves propagating
through the
honeycomb lattice completely lose their effective mass,
which results in quasiparticles that are described by a
Diraclike equation rather than the Schrodinger
equation. The latter which was so successful for the
understanding of quantum properties of other materials
does not work for graphene as charge carriers with zero
rest mass.
It also exhibits an astonishing electronic quality. Its
electrons can cover submicron distance without
scattering, even in samples placed on an atomically
rough substrate,
covered with adsorbates and at room T. Due to the
massless carriers and little scattering, quantum effects
in graphene are robust and can survive even at room T.
Graphene differs from most conventional three-
dimensional materials. Intrinsic graphene is a semi-
metal or zero-gap. Experimental results from transport
measurements show that graphene has a remarkably
high electron mobility at room temperature, with
reported values in excess of 15,000 cm2·V−1·s−1.
Additionally, the symmetry of the experimentally
measured conductance indicates that the mobilities for
holes and electrons should be nearly the same.[10] The
mobility is nearly independent of temperature between
10 K and 100 K.
XI. POTENTIAL APPLICATIONS
Several potential applications for graphene are
under development, and many more have been
proposed. These include lightweight, thin, flexible, yet
durable display screens, electric circuits, and solar
cells, as well as various medical, chemical, and
industrial processes enhanced or enabled by the use of
new graphene materials.
Integrated Circuits
Graphene due to its high moblility find its use in i.c.
allowing it to be used as the channel in a field-effect
transistor.
Transparent conducting electrodes
Graphene's high electrical conductivity and high
optical transparency make it a candidate for transparent

5. conducting electrodes, required for such applications as
touchscreens, liquid crystal displays, organic
photovoltaic cells, and organic light-emitting diodes.
Distillation and Desalination of Water
It is observed that graphene is impermeable to all
other liquids and gases except water. The quality which
finds immense advantage in purification of water.
Making water available to masses.
Single-molecule gas detectors
In detectors, The thin polymer layer acts like a
concentrator that absorbs gaseous molecules. The
molecule absorption introduces a local change in
electrical resistance of graphene sensors. While this
effect occurs in other materials, graphene is superior
due to its high electrical conductivity (even when few
carriers are present) and low noise, which makes this
change in resistance detectable up to a single atom.
Ultra-capacitors
Due to the extremely high surface area to mass ratio
of graphene, one potential application is in the
conductive plates of ultra-capacitors. To turn graphene
into a capacitor you take two graphene sheets and place
a polymer electrolyte between them, then cover it with
plastic insulator as you would a wire. The result is thin,
flexible, has more than 17 times the conductivity of
other materials, and it won't degrade even after cycling
through 10,000 charges. It is believed that graphene
could be used to produce ultra-capacitors with a greater
energy storage density than is currently available. Also
it was seen that its recharge rate is extremely fast while
draining at a normal rate. Due to this property one day
it can replace batteries.
Bionic Devices
Due to its flexibility and transparency it can be used
as an electrode for receiving signals from and to brain.
Also it is biodegradable possessing no harm to tissues.
Graphene is resistant to the salty ionic solutions
inside living tissue, so bionic devices made of graphene
could have long shelf lives, perhaps lasting a lifetime.
This is in contrast to metallic parts that can corrode
after a few years, possibly releasing toxic metals into
the body.
Transistors
A graphene hall bar with gold contacts on Si
substrate, its conducting state can be affected by
applying an electric field to Si. The transistors made of
graphene can be very thin and can run at higher
frequency and more efficiently than silicon transistors.
Protective Coating
Graphene is resistant to powerfull attacks from acis,
alkali’s. So a thin layer of graphene on the surface
could give a boost in its surface properties. Car paints,
Steel structure could become corrode free.
Flexible solar panels
Graphene has sparked the interest of engineers who
are trying to make new, lightweight, and flexible solar
panels that could be used to cover the outside surface
of a building, in addition to the roof—which is already
being used.When a photovoltaic cell is sandwiched
between two sheets of graphene, light crosses the
sheets of graphene and hits the photovoltaic cell. As a
result, the photovoltaic cell generates electricity, which
is carried by the sheets of graphene.
These lightweight and flexible solar panels could be
molded to fit an automobile body or be wrapped
around furniture or clothing.
Foldable Mobile Phone
Touch screens made with graphene as their
conductive element could be printed on thin plastic
instead of glass, so they would be light and flexible,
which could make cell phones as thin as a piece of
paper and foldable enough to slip into a pocket. Also,
because of graphene’s incredible strength, these cell
phones would be nearly unbreakable. Scientists expect
that this type of touch screen will be the first graphene
product to appear in the marketplace.

6. Photo Detectors
Photodetectors are computer chips that convert
photons from light into electrical signals. Every digital
camera has one and they are made of silicon. Frank
Koppens and his colleagues at the Institute of Photonic
Sciences in Barcelona dotted a layer of graphene with
lead sulfide and created an ultra-sensitive and flexible
photodector that could lead to thinner cameras and
more lightweight night vision goggles.
Artificial Muscle
Sheets of graphene can crumple up like paper, but
they are difficult to flatten out. At Duke University
scientists recently attached graphene to a pre-stretched
rubber sheet and found that when the sheet was
relaxed, the graphene still adhered to the rubber even
though it was crumpled up. That led them to layer the
graphene with polymer, which expanded and
contracted when a current was run through it – a key
component in building artificial muscle.
Absorbing radioactive waste
Researchers at Rice University and Lomonosov
Moscow State University found that microscopic bits
of graphene oxide bind to radioactive contaminants,
turning them into clumps that can be easily collected.
XII. CONCLUSION
The wonder material Graphenes various properties
were high lighted. Potential applications of graphene
were discussed in and, during the last 2 years,
significant progress has been made along many lines
penciled in there. The major difference between now
and then is the advent of graphene’s mass production
technologies. This has dramatically changed the whole
landscape by making the subject of applications less
speculative and allowing the development of new
concepts unimaginable earlier.
Graphene, a two-dimensional carbon allotrope, has
emerged as one of the most fascinating nano-materials
of the century. Its distinct qualities have attracted great
interest in the fields of chemistry, biology, and physics.
Graphene has stimulated interest among scientists in
various fields because of its exceptional electronic,
optical, mechanical, thermal, and magnetic properties.
The unique nature of graphene makes it stand out and
applicable to various technologies and other purposes.
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