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Nanoscience and nanotechnology
Nanoscience and nanotechnology 17
Nanochemistry Lecture 1
Dr Charu Arora, Associate Professor, Department of ChemistryNanostructuresNanoscience and nanotechnology
• Nanoscience deals with the scientific study of
objects with sizes in the 1 – 100 nm range in
at least one dimension.
• Nanotechnology deals with using objects in
the same size range to develop products with
possible practical application. It is usually
based on nanoscience insights.Nanoscience and Nanochemistry
• Nanoscience is interesting in part of course
because it by definition is new. But a more
profound and important reason is that it deals
with objects which are only slightly larger than an
atom. This means that the properties of the
objects can be influenced by direct
manifestations of quantum mechanics.
• It is also possible that nanoscale objects do
behave just like as expected from (semi)classical
physics, but the downgrading in size opens up
possible new applications.Research on nano• Nanotechnology is the creation of functional
materials, devices, and systems through control
of matter on the nanometer (1 to 100 nm) length
scale and the exploitation of novel properties and
phenomena developed at that scale.
• A scientific and technical revolution has begun
that is based upon the ability to systematically
organize and manipulate matter on the
nanometer length scale.Ancient nanotech.
• It is interesting to note that there has been
use of what now would definitely be called
nanoscience much before the advent of the
• - Vases used by old Greeks and RomansNanotechnology marketNanoscaleDefining Nanoscale
Nano - Dwarf
Nano size: 1 nm = 10 millimeter (mm) = 10 meter (m) nm
Combination of atoms or molecules to form objects of nanometer scale
Cross section of human hairCarbon nanostructuresImportance of nanoscale
• The wavelike properties of electrons inside matter are
influenced by variations on the nanometer scale. By
patterning matter on the nanometer length, it is
possible to vary fundamental properties of materials
(for instance, melting temperature, magnetization,
charge capacity) without changing the chemical
• The systematic organization of matter on the
nanometer length scale is a key feature of biological
systems. Nanotechnology promises to allow us to place
artificial components and assemblies inside cells, and
to make new materials using the self-assembly
methods of nature. Importance of nanoscale
• Nanoscale components have very high surface
areas, making them ideal for use in composite
materials, reacting systems, drug delivery, and
• The finite size of material entities, as compared
to the molecular scale, determine an increase of
the relative importance of surface tension and
local electromagnetic effects, making
nanostructured materials harder and less brittle.
• The interaction wavelength scales of various
external wave phenomena become comparable
to the material entity size, making materials
suitable for various opto-electronic applications. •Nano-materials: Used by humans for 100 of years, the beautiful ruby red
color of some glass is due to gold Nano particles trapped in the glass (ceramic)
•The decorative glaze known as
luster. Ruby Red glass pot
(entrapped with gold
What’s special with Nano?
The properties of nanomaterials deviate from those of single crystals or polycrystals
(bulk). For example, the fundamental properties like electronic, magnetic, optical,
chemical and biological Surface properties: energy levels, electronic structure, and
reactivity are different for nano materials.
Exhibit size dependent properties, such as lower melting points, higher energy
gaps etc. On the Surfaces and interfaces basics:
Bulk. In bulk materials, only a Nano. In nanomaterials, large no.
relatively small percentage of of atomic features near the
atoms will be at or near a interface.
surface or interface (like a
crystal grain boundary).
• Nanoporous materials
• Other structuresBulk and Nanoscale
Density of states for 3D, 2D, 1D, 0D showing discretization of energy and discontinuity of DOSElectrons in nanoparticles as particle in
a box modelEffects of Nano size
• Properties depends on size, composition and structure
• Nano size increases the surface area
• Change in surface energy (higher)
• Change in the electronic properties
• Change in optical band gap
• Change in electrical conductivity
• Higher and specific catalytic activity
• Change thermal and mechanical stabilities
• Different melting and phase transition temperatures
• Change in catalytic and chemical reactivitiesBulk and Nanoscale
Bulk (eg. Gold) Nano (eg. Gold)
1. Lustrous–Shiny surface when 1. Vary in appearance depending on
polished. size & shape of cluster.
2. Malleable–Can be hammered, 2. Are never gold in colour.
bent or rolled→any desired shape. 3. Are found in a range of colours.
3. Ductile–Can be drawn out into 4. Are very good catalysts.
wires 5. Are not “metals” but are
4. Yellow colour when in a mass semiconductors.
5. Heat & electricity conductor 6. Melts at relatively low temperature
6. High densities (940º C).
7. High melting point (1080 C) 7. Size & Shape of the nanoparticles
8. Tough with high tensile strength determines the color.
9. Inert-unaffected by air and most 8. For example; Gold particles in
25 nm — Red reflected
50 nm — Green reflected
(Unexpected visible properties & they
are small enough to scatter visible
light rather than absorb)