Liquid is one the three principal states of matter and its properties are known
to be intermediate between gaseous and solid phases. Several types of intermolecular
forces, categorised into long range and short range, play important roles in defining
liquid structure. Long range forces are of three types, namely electrostatic, induction
and dispersion, whilst the short range forces are of quantum chemical nature, due to
exchange of electrons. A wide range of materials, including elements, oxides, mixtures
of salts and dilute acids, are known to form glasses, which are non−crystalline,
amorphous matter. Methods such as lattice theories have been devised long time back
to understand the structure of liquids. Several other theories have been put forward as
well in order to explain complex behaviour of liquids at lower temperature such as
formation of highly viscous glassy materials. Most notable theoretical propositions
include Adam – Gibbs theory, Mode Coupling Theory and Energy Landscape theory.
Inherent Structure (IS) analysis is a powerful tool to identify the fundamental structures
of the system under investigation, and to obtain a pictorial characterisation of the
energetics between strong and fragile glasses. Relaxation times exhibit two distinct
kinetics, alpha and beta relaxations, which can be properly explained by Mode
Coupling Theory. Aqueous solutions of sugars and alkali salts such as lithium chloride
are known to be good glass formers, which require only low cooling rates in order to
form glasses, bypassing crystallisation.
Keywords: Atactic polymer, Expansion coefficient, Fragile, Freezing, Glass
transition, Hole theory, Inherent structures, Kauzmann’s paradox, Lindemann
ratio, London forces, Metastable, Strong liquids.
