In
solid-state physics, an orientational glass is a molecular
solid
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...
in which
crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...
line
long-range order
In physics, the terms order and disorder designate the presence or absence of some symmetry or correlation in a many-particle system.
In condensed matter physics, systems typically are ordered at low temperatures; upon heating, they undergo one o ...
coexists with quenched disorder in some
rotational degree of freedom.
An orientational glass is either obtained by quenching a
plastic crystal A plastic crystal is a crystal composed of weakly interacting molecules that possess some orientational or conformational degree of freedom. The name plastic crystal refers to the mechanical softness of such phases: they resemble waxes and are easil ...
, (e.g.
cyclohexane,
levoglucosan
Levoglucosan (C6H10O5) is an organic compound with a six-carbon ring structure formed from the pyrolysis of carbohydrates, such as starch and cellulose. As a result, levoglucosan is often used as a chemical tracer for biomass burning in atmospheri ...
), or it is a mixed crystal in which positional disorder causes additional disorder of molecular orientations, e.g. CN orientations in
KCN:
KBr.
References
Condensed matter physics
Crystallography
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