In solid-state physics, an orientational glass is a molecular solid in which crystalline long-range order coexists with quenched disorder in some rotational degree of freedom. An orientational glass is either obtained by quenching a plastic crystal, (e.g. cyclohexane, levoglucosan), or it is a mixed crystal in which positional disorder causes additional disorder of molecular orientations, e.g. CN orientations in KCN:KBr.
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