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).
