Thermal properties and Brillouin-scattering study of glass, crystal, and glacial states in n-butanol

We investigated through noncommercial calorimetry and elastoacoustic Brillouin experiments the phase diagram of n-butanol and measured the specific heat and the thermal conductivity in a wide low-temperature range for its three different states, namely, glass, crystal, and the so-called glacial states. The main aim of the work was to shed light on the controversial issue of these allegedly polyamorphic transitions found in some molecular glass-forming liquids, first reported to occur in triphenyl phosphite and later in n-butanol. Our experimental results show that the obtained glacial state in n-butanol is not a homogenous, amorphous state, but rather a mixture of two different coexisting phases, very likely the (frustrated) crystal phase embedded in a disordered, glassy phase.