ABSTRACT
Nanostructured materials have been de¢ned as materials that have at least one dimension in the “nanoscale” (typically 1-100 nm). ¡us, depending on the dimensions in which the length scale is nanoscale, they can be classi¢ed into (a) nanoparticles, (b) layered or lamellar structures, (c) ¢lamentary structures, and (d) bulk nanostructured materials (Siegel, 1994). Examples of nanoparticles, which can be considered to be of “zero” dimensionality, include a wide range of nanoscale powders of interest for diverse applications such as dispersions in cosmetics and pharmaceuticals. Quantum dots for optoelectronic applications may also fall into this category. A layered or lamellar structure is a 1D nanostructure in which the magnitudes of length and width are much greater than the nanoscale thickness. ¡in ¢lms for electronic device applications are examples of this category. Two-dimensional nanostructures have the length much larger than the width or diameter; nanowires or nanotubes may ¢t this division. ¡e nanostructures that contain the “bulk” de¢nition relevant to this chapter are 3D and consist of crystallites, or in certain cases quasicrystals and/or amorphous material that are nanoscale in dimension.
