Graphite is an allotrope of carbon that occurs naturally and is the most stable form of carbon under standard conditions. It consists of weakly bound layers of graphene stacked into a hexagonal structure. Graphite is a good conductor of heat and electricity and is very soft and slippery to the touch. It has a variety of applications including use in pencils, lubricants, batteries, and refractories due to its properties. Graphite can also be synthesized in the laboratory by heating sucrose with concentrated sulfuric acid to produce a black carbon material.

1. GRAPHITE

2. What is graphite?
The term graphite is derived from the Greek word “graphein,” which means to write. Graphite
is formed when carbon is subjected to the intense heat and pressure of the earth crust and upper
mantle.
Graphite formed by the pyrolysis of oriented organic polymer fibers is the basis of carbon
fibers.
 Graphite is an aloe trope of carbon which is grayish-black in color, opaque, and has a radiant
black sheen.
The aqueous solution of graphite is known as Aqua dog first stop graphite is also known as
plumbago.
Also called black lead. The term black lead usually refers to a powdered or processed graphite,
matte black in color.
It consists of weakly bound layers of graphene stacked into a hexagonal structure. Graphite
occurs naturally and is the most stable form of carbon under standard conditions.
Under high pressures and temperatures, it converts to diamond.

3. Occurrence:
 Graphite occurs naturally and is the most stable form of carbon
under standard conditions.
 Graphite occurs in metamorphic rocks as a result of the
reduction of sedimentary carbon compounds during
metamorphism. It also occurs in igneous rocks and in
meteorites. Minerals associated with graphite include quartz,
calcite, micas and tourmaline.
 In meteorites, graphite occurs with troilite and
silicate minerals.
 Small graphitic crystals in meteoritic iron are
called cliftonite.
 Graphite may be the second or third oldest
mineral in the Universe.

4. Hexagonal Structure(ABAB):
 Crystals of graphite contain layers of interlocking hexagons.
 Graphite is an allotrope of carbon. Each carbon atom is linked with 3 other carbon atoms 120
degrees apart by single covalent bond resulting in the hexagonal ring which is arranged in a
layer. It has 2-dimensional layers like structure. It is also called a sandwich-like structure. In
the structure of graphite, each carbon atom is 𝒔𝒑𝟐
hybridized and hexagon are arranged in
layers.
 Atoms in the plane are bonded covalently, with only three of the four potential bonding sites
satisfied. The fourth electron is free to migrate in the plane, making graphite electrically
conductive.
 The 4th valence of carbon Atom is satisfied by week wonder walls forces between 2 layers.
 Bonding between layers is via weak van der Waals bonds, which allow layers of graphite to be
easily separated, or to slide past each other. Electrical conductivity perpendicular to the layers is
consequently about 1000 times lower.
 The individual layers are called graphene. In each layer, the carbon atoms are arranged in a
honeycomb lattice. The C-C bond length is 0.142 nm within the layer and C-C distance between
2 layers is 0.34 nm.

6. ABCABC Stacking:
This stacking also contains layers of interlocking hexagons, but the layers are stacked
ABCABC.
Band Structure:
 Each carbon can be thought of as having three single bonds to the neighboring
carbons. This leaves one valence electron per carbon in a p-orbital at right angles to
the plane of the layer. These p-orbitals combine to form delocalized orbitals that
extend over the whole layer. If the layer contains n carbon atoms, then n orbitals are
formed, and there are n electrons to fit in them. Thus, half of the delocalized orbitals
are filled.
 Were the orbitals to form one band, this would explain the conductivity of graphite
very nicely, since there would be a half-filled band confined to the layers. The
situation is close to this, but not quite as simple. The delocalized orbitals, in fact,
form two bands, one bonding and one antibonding. The lower band is full and the
upper band empty. Graphite is a conductor because the band gap is zero, and thus
the electrons are readily promoted to the upper band. Because the density of states is
low at the Fermi level, the conductivity is not as high as that for a typical metal.

7. Types of Graphite
Alpha graphite(hexagonal):
Beta graphite(rhombohedral):
01
02
 In Alpha graphite, the layers are
arranged in the sequence of
ABAB arrangement.
 Alpha form can be converted to
the beta form through mechanical
treatment.
 In beta graphite, the layers are arranged in
the sequence of ABCABC. Energetically
less stable and less common.
 Beta form reverts to the alpha form when it
is heated above 1300 °C.
 These are classified as the arrangement of the carbon atoms.

8. Classification of Graphite:
Graphite can be divided into two main types:
1. Natural
2. Synthetic
1. Natural Graphite:
• Natural graphite is a mineral composed of graphitic
carbon. It varies considerably in crystallinity. Most of the
commercial (natural) graphite are mined, and usually
requires a considerable amount of mineral processing like
froth flotation to concentrate the graphite.
• Natural graphite is an excellent conductor of heat and
electricity, stable over a broad range of temperatures, and a
highly refractory material with a high melting point of
3650 °C.

9. 1. Crystalline Graphite 2. Amorphous Graphite
3. Flake Graphite
• Crystalline vein graphite came from crude oil deposits
that have transformed into graphite through time,
temperature, and pressure.
• Lump graphite (vein graphite) occurs in fissure veins or
fractures and appears as massive platy intergrowths of
fibrous or acicular crystalline aggregates and is
probably hydrothermal in origin.
• Vein graphite fissures typically measure between 1cm
and 1m in thickness and usually have a purity of more
than 90%.
• It is the least graphitic form. Very fine
flake graphite is sometimes called
amorphous. It is still crystalline in nature .
• Amorphous graphite can be found as
minute particles in beds of mesomorphic
rocks. The graphite content varies from
25% to 85% according to the geological
environment.
• Crystalline small flakes of graphite occurs as isolated, flat, plate-like particles with
hexagonal edges if unbroken. When broken the edges can be irregular or angular.
• Flake graphite can be found in metamorphic rocks evenly spread through the body of
the ore or in concentrated lens-shaped pockets. The range of carbon concentrations
varies from 5% to 40%.
 There are three types of natural graphite:

10. 2. Synthetic Graphite:
Synthetic graphite can be produced from coke and pitch. Although this graphite
is not as crystalline as natural graphite, it is likely to have higher purity.
1. Electrographite
 There are two types of synthetic graphite:
Pure carbon produced from coal tar pitch and
calcined petroleum coke in an electric furnace.
2. Synthetic graphite
Produced by heating calcined petroleum pitch to
2800°C.

11. Intercalation compounds of Graphite:
 Because the bonding between the layers in graphite is weak, Graphite forms intercalation
compounds with some metals and small molecules.
 In these compounds, the host molecule or atom gets “sandwiched” between the graphite
layers, resulting in a type of compound with variable stoichiometry.
 The solids produced by reversible insertion of such guest molecules into lattices are known
as intercalation compounds.
 These compounds has importance as catalysts
and as electrodes for high-energy-density
batteries. Also, important to increase
applications of graphite.
 Graphite forms bond both with electron donors
and the electron acceptors to form useful
intercalated compounds.
 Some graphite intercalation compounds are
superconductors.

13. Formation of Intercalated compounds with electron donors:
 The most common example is alkali metals. The alkali metals enter the graphite between the layers and
produce strongly colored solids in which the layers of carbon atoms have moved further apart.
 For example, potassium forms a golden compound (KC8) in which the inter-layer spacing is increased by
200 pm . The potassium donates an electron to the graphite (forming K+) and the conductivity of the
graphite now increases because it has a partially full antibonding band.
Structure of KC8: K, blue; C, grey.
Diffusion of alkali metals in the first stage, graphite
intercalation compounds

14. Intercalated compounds with electron acceptor:
 In these compounds, the graphite layers donate
electrons to the inserted molecules or ions, thus
producing a partially filled bonding band. This
increases the conductivity, and some of these
compounds have electrical conductivity
approaching that of aluminum.
Graphite with 𝐹𝑒𝐶𝑙3
 Graphite form intercalated compounds with electron acceptors i.e.,
sulfate, 𝑁𝑂3−
,𝐶𝑟𝑂3, 𝐵𝑟2, 𝐹𝑒𝐶𝑙3 and 𝐴𝑠𝐹5.

15.  Some graphite intercalation compounds are superconductors.
 In graphite, the current is carried through the layers by delocalized p- electrons.
Layered structures in which the current is carried by d-electrons are common in
transition metal compounds, such as the disulfides of Ti, Zr, Hf, V, Nb, Ta, Mo
and W, and mixed lithium metal oxides.
 Intercalates with disulfides were found to be superconductors at very low
temperatures. It was hoped that by altering the interlayer spacing, a compound
that was superconducting at higher temperatures would be found.
 Unfortunately, it soon transpired that altering the spacing by inserting different
molecules had very little effect on the temperature at which superconductivity
appeared.
 It was concluded that the superconductivity was confined to the layers.

16. Properties of Graphite:
 Graphite is a distinct material as it displays the properties of both a
metal and a non-metal.
 Graphite is a non-metal because it is made up of carbon atoms.
However, one of its property that makes it behave like a metal. It is
the most stable form of carbon because graphite is favored by high
pressure and high temperature but much stable form of carbon then
diamond.
 Although graphite is flexible, it is not elastic.
 It is also chemically inert and highly refractory.
 Displays low adsorption of X-rays and neutrons, due to which it is
very valuable in nuclear applications.
 Graphite has a high degree of anisotropy.
 Lighter than diamond, smooth and slippery to touch.
 A good conductor of electricity( Due to the presence of free electrons) and good conductor of heat.
 Very soapy to touch, Non-inflammable.
 Soft due to weak Vander wall forces.
 When burns in air carbon dioxide gas formed.
 Crystals of graphite are good conductors in two dimensions

17. Applications of Graphite
 Graphite is used in pencils and lubricants. It is a good conductor of heat and electricity.
 Its high conductivity makes it useful in electronic products such as electrodes, batteries,
and solar panels. Graphite is also used as a support for several industrially important
catalysts.
Chemical Industry:
Has high-temperature applications, like in the production of phosphorus and calcium carbide
in arc furnaces.
Graphite is used as an anode in specific aqueous electrolytic processes such as the production
of halogens (chlorine and fluorine).
Nuclear Industry:
Large amounts of high-purity electrographite are used for producing moderator rods and
reflector components in nuclear reactors. The suitability of electrographite comes from its low
absorption of neutrons, high thermal conductivity, and high strength at higher temperatures.
Electrical Applications:
Graphite is mainly used as an electrical material in the manufacture of carbon brushes in
electric motors. Component’s service life and performance largely depend on grade and
structure.
Mechanical Applications:
Graphite is widely used as an engineering material across a variety of applications such as
piston rings, thrust bearings, journal bearings, and vanes. Carbon-based seals are used in the
fuel pumps and shafts of several aircraft jet engines.

18.  Refractory Materials:
 Due to high-temperature stability and chemical inertness, graphite is the perfect
candidate for refractory material.
 It is used in the production of refractory bricks as well as “Mag-carbon” refractory
bricks (Mg-C).
 Graphite is used to produce crucibles, ladles, and molds for holding molten metals.
 Used in the production of functional refractories for the continuous casting of steel.
 Graphite flake is mixed with alumina and zirconia, and then isostatically pressed to
create components like stopper rods, subentry nozzles, and ladle shrouds used for
regulating the flow of molten steel and also for safeguarding against oxidation.
This type of material could also be used as protection for pyrometers.
 In the production of iron, graphite blocks are used to produce a portion of the
lining of the blast furnace.
 The electrodes used in many electrical metallurgical furnaces are mass-produced
from graphite, for instance, the electric arc furnaces used for processing steel.

19.  Amorphous graphite Application: used in
 Metallurgy
 Coatings
 Lubricants
 Refractories
 Paint production
 Pencil production
 Crystalline graphite Applications: used in
 Lubricants
 Powder metallurgy
 Grinding wheels
 Batteries
Flake Graphite Applications: used in
 Flake graphite is used in refractory applications, typically in secondary steelmaking.
 Also used in pencils, powder metallurgy, coatings, and lubricants.
 Many of the sources of natural graphite are also used in the development of graphite foil.
 Synthetic graphite Applications: used in
 Aerospace applications
 Carbon brushes
 Graphite electrodes for electric arc furnaces, for metallurgical processing
 Moderator rods in nuclear power plants
 Batteries
 Scientific research
 Neutron moderator
 Powder and scrap

20. Graphite Preparation in Laboratory
Graphite is a brittle steel black coloured compound that is used in several different
industrial inductor processes as well as in the lady for your pencil.
To make graphite in the lab we need:
Chemicals:
1) 10- 15 gram of sucrose, 2) 10 mils of 18 molar sulphuric acid, 3) 10- 20 grams of
sodium bicarbonate, 4) 250 mil beaker, 5) a stirring rod, 6) 10 ml graduated cylinder and a
plastic zip-lock bag.
Procedure:
 Firstly placed 10 millilitres of 18 molar sulphuric acids in a 10 millilitre graduated
cylinder.
 Place 15 grams of sucrose in a 50-millilitre beaker.
 Now pour the 10 mils of punch chisel, Cassatt, into sucrose. Stir it briskly.
 We will notice the reaction is taking place as the materials get darker and eventually
turned black.
 After some time the reaction completes and the result is the graphite.