Frozen-in states of orientational and positional disorder in molecular solids

Abstract

It has previously been shown that the ordinary liquid–glass transition is just one example of a class of “glass transitions” due to loss of equilibrium which may occur widely in metastable phases of condensed matter. In the present paper, glass-transition phenomena occurring in stable crystalline phases of SnCl₂.2H₂O, H₃BO₃, H₂O, pinacol hexahydrate, CO and TINO₂ crystals are investigated. Deuteration effects on the kinetic properties of the freezing process are also reported. These glassy crystals differ from those realized in undercooled metastable phases in that they never encounter the Kauzmann paradox and are considered to belong to a new category of the state of aggregation of matter. Throughout the present studies, the usefulness of adiabatic calorimetry for the investigation of slow molecular motion in solids will be stressed, for which conventional spectroscopic techniques such as dielectric measurement are impractical because of the prolonged relaxation time.