Evidence for a supercooled plastic-crystal phase in solid ethanol.

Departamento de Fi´sica de la Materia Condensada, Universidad de Sevilla, and Instituto de Ciencia de Materiales,Consejo Superior de Investigaciones Cienti´ficas, Facultad de Ciencias, P.O. Box 1065, E-41080 Sevilla, Spain~Received 18 October 1995; revised manuscript received 8 December 1995!The existence of an orientationally disordered cubic phase of solid ethanol is revealed by x-ray diffractionand Raman spectroscopic measurements. Such a phase, whose existence was postulated some time ago on thebasis of specific-heat measurements, is produced by quenching below some 95 K a plastic crystal formed uponmelting and subsequent annealing of the topologically disordered ~glassy! solid. The relevance of the presentfindings for current discussions on glassy dynamics is analyzed in some detail.