Low-temperature specific heat of molecular glasses and crystals

Abstract

We have measured the low-temperature specific heat C p of several glass-forming alcohols. Special attention has been paid to ethanol, either hydrogenated or deuterated, in its different solid phases (fully ordered crystal, disordered crystal or orientational glass, and true structural glass). New measurements have been carried out on 1- and 2-propanol (for crystal and glass states) and on the glass phase of glycerol. The comparison of the isotopic effects in ethanol, as well as that with two isomers of propanol, provide a unique benchmark to study the relative importance of different kinds of disorder. In this work, the whole set of maxima in C p / T 3 is discussed in the framework of the scaling procedure of Liu and Löhneysen [Europhys. Lett. 33 (1996) 617].