about nano particles

1. 1.Carbon Nano Tubes
Carbon nano tubes were first discovered by sumio lijima in
1991. CNT’s are extended tubes of grapheme sheets;
There are two types of CNT’s:
a) single-walled
b) multi-walled.
Single walled is 1nm of diameter and Multi walled is 10nm
of diameter.
These tubes are capable of storing hydrogen gas in fuel-
cell in car.These tubes are 100 times stronger than steel.
They can hold 8% by weight of hydrogen. In cars instead
of keeping large tanks for gas we use nano tubes for
storing hydrogen gas. These are efficiently used for this
purpose. Carbon nano tubes are large molecules of pure
carbon that are made of thin,long and thousands of nano
meters long.
Carbon nano tubes are made of laser evaporation
method. In this method, graphite and nickel catalyst and
heated upto 1200 degrees centigrade and then the
material is irradiated with laser.
Properties:
• They are highly elastic and can withstand structural
distortions.
• They are resistant to attack by chemicals and
oxygen.
• They are extremely light in weight. Single walled has
density of 0.8 g/cc and Multi walled has density of
1.8g/cc.
• Due to presence of c-c bond, they possess
remarkable strength.
ELECTRICAL PROPERTIES:
They vary between semi-conducting to metallic
depending on diameter and chirality of the tube.

2. MECHANIOCAL PROPERTIES:
These are quiet unique.
2.Fullerenes
In the mid-1980s a new class of carbon material was
discovered called carbon-60. These are spherical molecules
about inm of diameter, comprising of 60 carbon atoms
arranged as 20 hexagons and 12 pentagons.