Nanoarchitecture: Morphogenesis and applications of nanostructured materials

Abstract

Nanomaterials are of immense scientific interest as they effectively bridge the gap between bulk materials and atomic or molecular structures. Bulk materials have constant physical properties regardless of its size, but at the nanoscale, this is often not the case. However, at nanoregime, many of the properties (electronic, optical, thermodynamic, magnetic and mechanical) of metals and semiconductors are in between bulk and atoms (2-4). For example, bending of bulk copper wires/ribbons occurs with movement of copper atoms/clusters at about 50 nm scale. Copper nanoparticles smaller than 50 nm are considered super hard materials that do not exhibit the same malleability and ductility as bulk copper (5). The change in properties is not always desirable. Ferroelectric materials smaller than 10 nm can switch their magnetization direction using room temperature thermal energy, thus making them useless for memory storage (6). Decrease in melting temperature has been observed with decreasing nanocrystal size in the case of Au, Sn, Pb and CdS nanoparticles (7-9). Sintering is also possible for nanoparticles at lower temperatures and over shorter durations than for larger particles (5).