Nanomaterials are materials that have at least one dimension sized between 1 to 100 nanometers. They have unique properties compared to larger materials due to increased surface area to volume ratio and quantum effects. Nanomaterials can be synthesized through top-down methods that break down bulk materials or bottom-up techniques that build up atoms and molecules. They have a variety of applications including in electronics, energy storage, medicine and more due to their small size and novel characteristics.
HOA1&2 - Module 3 - PREHISTORCI ARCHITECTURE OF KERALA.pptx
Nanomaterials
1. 12/4//2015
1
UNIT - V
Nanomaterials
Introduction
Nano means 10-9. ( Nanometer is billionth of a meter)
Nanomaterials (nanocryatalline materials) are materials possessing sizes on
the order of a billionth of a meter.
(or)
Nanomaterials could be defined as the materials with at least one
of its dimensions in the range of a nano meter.
All materials are composed of grains, which in turn comprise many
atoms. These grains are usually invisible to the naked eye, depending
on their size.
Conventional materials have grains varying in size from 100’s of
microns (μm) to millimeters (mm)
2. 12/4//2015
2
Nano Technology
Nanotechnology can be defined as the design,
characterization, production and application
of structures devices and systems by
controlling shape and size at a Nano meter
Scale.
4. 12/4//2015
4
Why Properties of Nano Materials are different ?
The properties of Nano Materials are very much
different from those at a larger scale.
Two principal factors cause the properties of Nano
Materials to differ significantly from other materials.
1.Increase in surface to volume ratio.
2.Quantum confinement effect.
These factors can charge or enhance properties such as
reactivity , strength and electrical characteristics.
Increase in a Surface Area to Volume ratio
Nano Materials have a relatively larger Surface area when
compared to the same volume or mass of the material
produced in a larger form.
Let us consider a Sphere of radius “r”.
Its Surface Area =4πr2.
Its volume= 4/3πr3
Surface Area to Volume Ratio= 3/r.
Thus when the radius of the Sphere decreases , its
Surface to Volume ratio increases.
6. 12/4//2015
6
2
2
18
27
)
3
1
(
6 m
m
area
surface
m
3
1
Let us consider one Cubic Volume shown in figure its the
Surface Area is 6m2 .
When it is divided into eight pieces its Surface Area
becomes 12m2, similarly When the same volume is
divided into 27 pieces its Surface Area becomes 18m2.
Thus we find that when the given volume is divided into
smaller pieces the Surface Area increases.
Hence as particle size decreases a greater proportion of
atoms are found at the surface compared to those inside.
Nano particles have a much greater surface area per given
volume compared with larger particles. It makes materials
more Chemically reactive.
7. 12/4//2015
7
Synthesis of nanomaterials
Bulk
Powder
Nanoparticles
Top Down method Bottom Up method
Nanoparticles
Clusters
Atoms
Sol-gel technique
Zr[OCH(CH3)]4.(CH3)2COOH Zirconium chloride
TOPO
60oC, Argon Atm.
340oC
Stirring
Cooled 60oC
Zirconia Nanoparticle
Precipitation
Washing
Calcination
800oC
Acetone
