Nanotechnology lecture2

NANOTECHNOLOGY
: Prof. Ninad Mehendale

What we learnt last time
2017 Prof. Ninad Mehendale 2

What we learnt last time

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What is Carbon
Carbon is a chemical element with symbol C and atomic number 6. It is
nonmetallic and tetravalent making four electrons available to form
covalent chemical bonds.

Carbon products

Carbon products
Diamond is a metastable allotrope of
carbon, where the carbon atoms are
arranged in a variation of the face-
centered cubic crystal structure called a
diamond lattice. Diamond is less stable
than graphite, but the conversion rate
from diamond to graphite is negligible at
standard conditions.

Carbon products
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
colorless crystal. Colors in diamond
originate from lattice defects and
impurities.

Carbon products
impurities.

Carbon products

What is fullerene.
a form of carbon having a large spheroidal molecule consisting of a
hollow cage of sixty or more atoms, of which buckminsterfullerene was
the first known example. Fullerenes are produced chiefly by the action of
an arc discharge between carbon electrodes in an inert atmosphere.

What is fullerene.
Fullerenes consist of 20 hexagonal and 12 pentagonal rings as the basis
of a closed cage structure .

What is fullerene.

What is C60.
Buckminsterfullerene (or Bucky-ball) is a
spherical fullerene molecule with the formula
C60. It has a cage-like fused-ring structure
(truncated icosahedron) which resembles a
football (soccer ball), made of twenty hexagons
and twelve pentagons, with a carbon atom at
each vertex of each polygon and a bond along
each polygon edge.

What is C60.
High-vacuum
electrolysis of a C60-
fullerene derivative.
Slow diffusion into the
anode (right side)
yields the characteristic
purple color of pure
C60.

What is alternative to C60.

Types of compounds of fullerenes
Compounds of fullerenes may be classed according to two different
categories: Exohedral (inside the cage) and Endohedral (outside the
cage).

How fullerenes are formed
• Combustion flame synthesis

Combustion?

Combustion?
The process of burning something.

Combustion?
The process of burning something.
Rapid chemical combination of a substance with oxygen, involving the
production of heat and light.

Flame?
A flame is the visible, gaseous part of a fire. It is caused by a highly
exothermic reaction taking place in a thin zone. Very hot flames are hot
enough to have ionized gaseous components of sufficient density to be
considered plasma.

Flame colors?
Temperature

Flame colors?
Color tells us about the temperature of a candle flame. The inner core of
the candle flame is light blue, with a temperature of around 1670 K (1400
°C). That is the hottest part of the flame. The color inside the flame
becomes yellow, orange, and finally red. The further you reach from the
center of the flame, the lower the temperature will be. The red portion is
around 1070 K (800 °C).

Flame colors?
Temperature
Fuel

What is combustion flame synthesis

Q.1 Explain combustion flame synthesis [10M]

How fullerenes are formed
• Combustion flame synthesis
• Crystal formation

What is Crystal?
A crystal or crystalline solid is a solid material whose constituents (such
as atoms, molecules, or ions) are arranged in a highly ordered
microscopic structure, forming a crystal lattice that extends in all
directions.
Examples of large crystals include snowflakes, diamonds, and table salt.

Q. 2 Explain in detail process of crystal formation for
fullerene production? [5M]

Nanotechnology lecture2

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