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Nanomaterials – An Introduction
C. N. R. Rao, A. Mu ¨ller, and A. K. Cheetham
The term nanotechnology is employed to describe the creation and exploitation of
materials with structural features in between those of atoms and bulk materials,
with at least one dimension in the nanometer range (1 nm ¼ 10
À9 m). In Table
1.1, we list typical nanomaterials of different dimensions. Properties of materials
of nanometric dimensions are significantly different from those of atoms as well as
those of bulk materials. Suitable control of the properties of nanometer-scale
structures can lead to new science as well as new devices and technologies. The
underlying theme of nanotechnology is miniaturization. The importance of nanotechnology was pointed out by Feynman as early as 1959, in his often-cited lecture
entitled ‘‘There is plenty of room at the bottom’’. The challenge is to beat Moore’s
law, according to which the size of microelectronic devices shrinks by half every
four years. This implies that by 2020, the size will be in the nm scale and we
should be able to accommodate 1000 CDs in a wristwatch, as predicted by Whitesides.
There has been an explosive growth of nanoscience and technology in the last
few years, primarily because of the availability of new strategies for the synthesis of
nanomaterials and new tools for characterization and manipulation (Table 1.2).
There are many examples to demonstrate the current achievements and paradigm
shifts in this area. Scanning tunneling microscope (STM) images of quantum dots
(e.g. germanium pyramid on a silicon surface) and of the quantum corral of 48 Fe
atoms placed in a circle of 7.3 nm radius being familiar ones (Figure 1.1). Several
methods of synthesizing nanoparticles, nanowires and nanotubes, and their assemblies, have been discovered. Thus, nanotubes and nanowires of a variety of
inorganic materials have been discovered, besides those of carbon. Ordered arrays
or superlattices of nanocrystals of metals and semiconductors have been prepared.
Nanostructured polymers formed by the ordered self-assembly of triblock copolymers and nanostructured high-strength materials are other examples.
Besides the established techniques of electron microscopy, diffraction methods
and spectroscopic tools, scanning probe microscopies have provided powerful
means for studying nanostructures. Novel methods of fabrication of patterned
nanostructures as well as new device and fabrication concepts are constantly being
1
Nanomaterials – An Introduction
C. N. R. Rao, A. Mu ¨ller, and A. K. Cheetham
The term nanotechnology is employed to describe the creation and exploitation of
materials with structural features in between those of atoms and bulk materials,
with at least one dimension in the nanometer range (1 nm ¼ 10
À9 m). In Table
1.1, we list typical nanomaterials of different dimensions. Properties of materials
of nanometric dimensions are significantly different from those of atoms as well as
those of bulk materials. Suitable control of the properties of nanometer-scale
structures can lead to new science as well as new devices and technologies. The
underlying theme of nanotechnology is miniaturization. The importance of nanotechnology was pointed out by Feynman as early as 1959, in his often-cited lecture
entitled ‘‘There is plenty of room at the bottom’’. The challenge is to beat Moore’s
law, according to which the size of microelectronic devices shrinks by half every
four years. This implies that by 2020, the size will be in the nm scale and we
should be able to accommodate 1000 CDs in a wristwatch, as predicted by Whitesides.
There has been an explosive growth of nanoscience and technology in the last
few years, primarily because of the availability of new strategies for the synthesis of
nanomaterials and new tools for characterization and manipulation (Table 1.2).
There are many examples to demonstrate the current achievements and paradigm
shifts in this area. Scanning tunneling microscope (STM) images of quantum dots
(e.g. germanium pyramid on a silicon surface) and of the quantum corral of 48 Fe
atoms placed in a circle of 7.3 nm radius being familiar ones (Figure 1.1). Several
methods of synthesizing nanoparticles, nanowires and nanotubes, and their assemblies, have been discovered. Thus, nanotubes and nanowires of a variety of
inorganic materials have been discovered, besides those of carbon. Ordered arrays
or superlattices of nanocrystals of metals and semiconductors have been prepared.
Nanostructured polymers formed by the ordered self-assembly of triblock copolymers and nanostructured high-strength materials are other examples.
Besides the established techniques of electron microscopy, diffraction methods
and spectroscopic tools, scanning probe microscopies have provided powerful
means for studying nanostructures. Novel methods of fabrication of patterned
nanostructures as well as new device and fabrication concepts are constantly being
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