Anisotropic microstructures of Au and Ag

Abstract

The prefix nano in ‘nanoscience’ means a billionth (1 × 10-9 ). It deals with various aspects of matter, having dimensions of the order of a billionth of a meter (1 nm). At the nanoscale, the fundamental properties of materials depend on their size, shape, and composition. When objects are below 100 nms in size, they tend to exhibit unusual chemical and physical properties Comparisons of objects are having different sizes from micrometer to nanometer [From ref 1]. For example, ZnO, an important semiconducting and piezoelectric material can be obtained in various shapes such as tubes, wires, rings and even other exotic forms such as springs, combs, belts and cages in nm range. Besides spherical nanoparticles of metals and semiconductors and carbon nanotubes [2, 3], other interesting shapes include nanotriangles, nanocubes, mesoflowers, nanoprisms, nanodisks and nanorings, junction nanotubes, nanowalls, nanoflowers etc. Such shapes may be derived from metals, semiconductors, oxides, nitrides, sulfides etc. Figure 1.2 shows electron micrographs of some interesting shapes of nanoobjects [4-10].