Partial-ordering of supercooled liquid ethanol into a rotator-phase crystal as an example of entropy-driven transitions

A rotator-phase (plastic) crystal phase is formed upon annealing supercooled liquid ethanol several degrees above the glass transition temperature. Such a transition is driven by an entropic mechanism which results in an increase of microscopic disorder within the crystal with respect to the liquid as monitored by the excess linewidth of the neutron quasielastic spectra of both phases.