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Introduction to Nanotechnology
2.2 Properties of Nanomaterials
In tandem with surface-area effects, quantum
effects can begin to dominate the properties of matter
as size is reduced to the nanoscale. These can affect the
optical, electrical and magnetic behaviour of materials,
particularly as the structure or particle size approaches
the smaller end of the nanoscale. Materials that exploit
these effects include quantum dots, and quantum well
lasers for optoelectronics.
For other materials such as crystalline solids, as the
size of their structural components decreases, there is
much greater interface area within the material; this can
greatly affect both mechanical and electrical properties.
For example, most metals are made up of small
crystalline grains; the boundaries between the grain
slow down or arrest the propagation of defects when
the material is stressed, thus giving it strength. If these
grains can be made very small, or even nanoscale in
size, the interface area within the material greatly
increases, which enhances its strength. For example,
nanocrystalline nickel is as strong as hardened steel.
Understanding surfaces and interfaces is a key challenge
for those working on nanomaterials, and one where
new imaging and analysis instruments are vital.
3. Nanomaterial Science
Nanomaterials are not simply another step in the
miniaturization of materials. They often require very
different production approaches. There are
several processes to create nanomaterials, classified as
‘top-down’ and ‘bottom-up’. Although many
nanomaterials are currently at the laboratory stage of
manufacture, a few of them are being commercialised.
Below we outline some examples of nanomaterials
and the range of nanoscience that is aimed at
understanding their properties. As will be seen, the
behaviour of some nanomaterials is well understood,
whereas others present greater challenges.
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