Mr. Rahul Dev
M.Sc [Polymer Science]
• In mineralogy Diamond is a metastable allotrope
• Diamond is less stable than graphite, but the
conversion rate from diamond to graphite is
negligible at standard conditions.
• Most natural diamonds are formed at high
temperature and pressure at depths of 140 to 190
kilometers (87 to 118 mi) in the Earth's mantle.
• The formation of natural diamond requires very
specific conditions exposure of carbon-bearing
materials to high pressure, ranging
approximately between 45 and 60 kilobars(4.5
and 6 GPa), but at a comparatively low
temperature range between approximately 900
and 1,300 °C (1,650 and 2,370 °F). These
conditions are met in two places on Earth; in
the lithospheric mantle below relatively
stable continental plates, and at the site of a
Structure Of Diamond
• In diamond, the carbon
atoms are arranged
hybridisation of C): each
C atom is linked to its
neighbours by four
single covalent bonds.
This leads to a three-
dimensional network of
Formula Mass: 12.01 gmol-1
Density: 3.5-3.53 g/m3
Colours: Typically Yellow, Brown or Gray to colourless.
Less often blue, green, black, translucent white, pink,
violet, orange, purple and red.
Crystal Structure: Octahedral
• Mechanical Hardness ~98 Gpa
• Compressive Strength > 110 Gpa
• Highest Bulk Modulus- 1.2*1012 N/M2
• Lowest Compressibility- 8.3*10-13 M2/N
• Highest Thermal Conductivity- 2*103 W/M/K
• Optically Transparent From Deep UV To Far IR
• Good Electrical Insulator- R~1016 Ω
• Highest Melting Point- 3820K
• Resistant To Corrosion By Acid Or Base
• Negative Electron Affinity
• Extreme Hardness
• High Thermal Conductivity
• Wide Bandgap And High Optical Dispersion
• Resistant To Scratching
• Excellent Electrical Insulators
• Diamond Are Naturaly Liophilic And Hydrophobic
• Diamonds Are Chemically Stable
• Diamond has a wide bandgap of 5.5 eV
corresponding to the deep ultraviolet
wavelength of 225 nanometers. This means pure
diamond should transmit visible light and
appear as a clear colourless crystal. Colours in
diamond originate from lattice defects and
impurities. The diamond crystal lattice is
exceptionally strong and only atoms of nitrogen,
boron and hydrogen can be introduced into
diamond during the growth at significant
• Nitrogen is by far the most common impurity
found in gem diamonds and is responsible for
the yellow and brown color in diamonds. Boron
is responsible for the blue color.
Hope Diamond, 45.52 carats (9.104 g), dark
Indian Kohinoor 105.602 carats
(21.1204 g) Finest White
• Synthetic diamonds are diamonds manufactured in a
laboratory, as opposed to diamonds mined from the
• The majority of commercially available synthetic
diamonds are yellow and are produced by so-called
High Pressure High Temperature (HPHT) processes
• Another popular method of growing synthetic diamond
is chemical vapour deposition (CVD). The growth occurs
under low pressure (below atmospheric pressure).
• Diamond Microdermabrasion offers intensive skin
exfoliating. This treatment is non-invasive and uses
a diamond encrusted tip to polish the skins surface
without harsh chemicals or messy crystals.
• It is used in protective windows for space probes as
it can keep out harmful radiations.
• Because of its extra-ordinary sensitivity to heat rays,
it is used in high precision thermometers.
• Sharp-edged diamonds are used by eye surgeons
remove cataract from eyes high precision.
• It is used in dies for the manufacture of tungsten
filaments for electric light bulbs.
Alternatives to Diamond
• Boron Nitride
o It’s hardness of 9.8 on the Mohs scale makes it very
useful for cutting tools and abrasives
o BN is isoelectronic with diamond, so it shares many
of its properties
• Tungsten Carbide
o Can substitute for diamond in many places
o Actually used in HPHT synthesis
• But diamond is still the best
• The mineral graphite is an allotrope of carbon.
• It was named by Abraham Gottlob Werner in 1789 from
the Ancient Greek "to draw/write", for its use in pencils,
where it is commonly called lead (not to be confused
with the metallic element lead).
• Graphite is the most stable form of carbon under
standard conditions. Therefore, it is used in
thermochemistry as the standard state for defining the
heat of formation of carbon compounds.
• Graphite was used by the 4th millennium B.C. Marita
culture to create a ceramic paint to decorate pottery
during the Neolithic Age in southeastern Europe.
• Historically, graphite was called black lead or plumbago
• Chemical Formula : C
• Colour: Silver Grey To Black
• Streak: Black
• Crystal Structure: Hexagonal 3D Crystal Atlas
• Crystal Forms and Aggregates :
Crystals consist of thin hexagonal plates or distorted
clusters of flaky plates on a matrix. Large thick
hexagonal crystals are rare. Most often occurs as veins
and in massive form, and can be very large in size.
Small, rounded ball-like aggregates and radiating
spheres also occur.
• Transparency: Opaque
• Luster : Metallic
• Tenacity : Brittle; thin flakes are flexible
• Other ID Marks :
1) Has a greasy feel.
2) Smudges the hands when touched.
3) Is a good conductor of electricity (although it is a poor
conductor of heat).
• In Group : Native Elements; Non-Metallic Elements
• Striking Features : Low weight, greasy feel, smudge, and low
• Environment : Most often in metamorphic rock caused from
the metamorphism of carbonates.
• Graphite occurs in metamorphic rocks as a result of the
reduction of sedimentary carbon compounds during
• It also occurs in igneous rocks and in meteorites.
• Minerals associated with graphite include quartz,
calcite,micas and tourmaline. In meteorites it occurs with
troilite and silicate minerals.
• Small graphitic crystals in meteoritic iron are called
Graphite has a layered, planar
structure. In each layer, the carbon
atoms are arranged in a honeycomb
lattice with separation of 0.142 nm,
and the distance between planes is
• The two known forms of graphite,
alpha (hexagonal) and beta
(rhombohedral) have very similar
physical properties, except that the
graphene layers stack slightly
differently. The hexagonal graphite
may be either flat or buckled
Graphite's unit cell 21
1. Ball and stick model of graphite (two graphene layers)
2. Side view of layer stacking
3. Plane view of layer stacking
• High Thermal Conductivity.
• High Thermal Shock Resistance.
• High Melting Temperature.
• Low Density (28% Of Steel).
• Low Hardness.
• Low Friction And Self Lubrication.
• Electrical Conductivity Highest Of Non-metallic Materials.
• Low Coefficient Of Thermal Expansion.
• High Strength (Particularly Compressive Strength), Which
Increases With The Temperature Rise.
• High Stiffness (Modulus Of Elasticity).
• High Thermal Resistance. Graphite Is Capable To Work In
The Temperature Range From Absolute Zero To 6330°F
(3500°C) In Inert Atmosphere.
• High Chemical And Corrosion Resistance;
• Good Oxidation Resistance. Graphite Starts To Be Oxidized
In Oxidizing Atmosphere At 932°F (500°C).
• Low Absorption Coefficient For X-rays.
• High Resistance To Neutron Radiation. Graphite Slows
Down Fast Neutrons And Scatters Thermal Neutrons.
• High Radiation Emissivity;
• Ability To Absorb Radio Waves;
• Low Wettability By Liquid Metals;
• Good Machinability;
• Ability To Absorb Gases.
• Graphite is mostly used in pencils, steelmaking,
expanded graphite, brake linings,batteries,foundry
facings and lubricants.
• As a lubricant at higher temperatures.
• As a refractory material of making crucibles and electrodes for
high temperature work.
• In electrotyping and in the manufacture of gramophone
records: Graphite is used for making the non-conducting
(generally wax) surface, so that electroplating can be done.
• For manufacturing lead pencils and stove paints.
• It is a component of printers’ ink.
Diamond Is Transparent Graphite Is Black And Opaque
Diamond Is A Poor Conductor Of
Electricity, But Is A Good Conductor Of
Graphite On The Other Hand Is A Good
Conductor Of Heat And Electricity.
Diamond Is Hardest Substance Known In
Graphite Is Soft And Slippery To Touch
Density Of Diamond Is More Density Of Graphite Is Comparatively
It Is Insoluble In All Solvents It Is Insoluble In All Ordinary Solvents
Diamond Is The Ultimate Abrasive Graphite Is A Very Good Lubricant
Diamond Crystallizes In The Isometric
Graphite Crystallizes In The Hexagonal
It Occurs As Octahedral Crystals It Occurs As Hexagonal Crystals
• Properties and Growth Of Diamond By G. Davies
• Applications of Diamond Films and Related Materials.
Elsevier. A . Feldman and L.H. Robins (1991).
• Optical Properties of Diamond: A Data Handbook.
Springer. A.M. Zaitsev (2001).