Abstract:
In Nature, disorder is more prevalent than order. In the realm of condensed matter, the most
common form of disorder we encounter is structural disorder. The epitome of structural disorder
is a glass, although crystals also possess some degree of disorder in the form of point defects,
dislocations and grain boundaries. In crystals, however, scientists have developed methods
to intelligently utilize these imperfections to enhance the functionality of materials. One such
striking example is the development of super plastic materials (Nieh et al. 2005). These materials
are achieved by engineering the architecture of grain boundaries, thin disordered interfaces that
separate crystallites of different orientations in a polycrystal. The characteristic attributes of
any material stem from its structure. For instance in the context of crystallization, at high
temperature the system is a fluid and does not posses any long-range order. However, once
it crystallizes, the onset of long range order leads to the development of rigidity. Further, the
degree of disorder dictates the mechanical properties of crystals. But as always, Nature surprises
us by providing exceptions to a general premise. One such popular example of matter is glass
which possess a liquid like structure but is rigid like a crystal. Despite decades of research very
little is known about glasses, how they form and what gives rise to rigidity. Numerous theories
have been formulated to understand amorphous solids. In this process, many new concepts arose
which have significantly contributed to other fields like protein folding (Bryngelson & Wolynes
1987) and computer science (Kirkpatrick et al. 1983) as well. However, the lack of understanding
of glasses did not hinder their utility. About 500 years ago, it was discovered that glasses offer
useful properties like high wear resistance, high fracture toughness, high porosity and many
more. Amorphous solids are therefore used routinely for numerous applications ranging from
window panes to artificial implants .
