Freezing of glycerol-water mixtures under pressure

• Published in: Journal of physics. Condensed matter Vol. 24; no. 32; pp. 325103, 1 - 325103
• Main Authors: Klotz, S, Takemura, K, Strässle, Th, Hansen, Th
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 15.08.2012; Institute of Physics
• Subjects: Condensed matter; Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Fluorescence; Freezing; Glass transitions; Glycerol-Water; Glycerols; Molecular dynamics; Neutron scattering; Phase separation; Physics; Specific phase transitions; Water; Glass transition; Pressure effects; Hydrogen bonds; Phase separation; Molecular dynamics method; Fluorescence; Glycerol; Binary mixtures; Neutron diffusion; Solidification
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/24/32/325103

We investigated freezing of pure glycerol as well as glycerol-water (GW) mixtures with 3:1 and 3:2 volume fractions as a function of pressure in the 0-10 GPa range by ruby fluorescence spectroscopy and neutron scattering. We find that the glass transition pressure increases from 5.5 GPa for pure glycerol to 6.5 GPa for the 3:1 GW mixture, with unusually small pressure gradients above. For higher water concentrations close to 3:2, phase separation occurs above 2 GPa where most of the water is expelled in the form of ice VII. The results suggest that glycerol is able to effectively hydrogen bond not more than 2.5 H2O molecules per glycerol, which seems to support conclusions from molecular dynamics simulations. The data indicate that these fluids could become important as pressure transmitting media for neutron scattering in the 0-7 GPa range, including at low temperatures.