Anomalies in bulk supercooled water at negative pressure.
Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144-6154], or emanate from a critical point terminating a liquid-liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727-737]. At positive pressure, the LMκT has escaped observation because it lies in the "no man's land" beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man's land at negative pressure.
Institut Lumière Matière, Unité Mixte de Recherche 5306 Université Lyon 1, Centre National de la Recherche Scientifique, Université de Lyon and Institut Universitaire de France, 69622 Villeurbanne Cedex, France; and.
Gaël
G
Pallares
Institut Lumière Matière, Unité Mixte de Recherche 5306 Université Lyon 1, Centre National de la Recherche Scientifique, Université de Lyon and Institut Universitaire de France, 69622 Villeurbanne Cedex, France; and.
Mouna
M
El Mekki Azouzi
Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Miguel A
MA
González
Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Juan L
JL
Aragones
Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
José L F
JL
Abascal
Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Chantal
C
Valeriani
Institut Lumière Matière, Unité Mixte de Recherche 5306 Université Lyon 1, Centre National de la Recherche Scientifique, Université de Lyon and Institut Universitaire de France, 69622 Villeurbanne Cedex, France; and frederic.caupin@univ-lyon1.fr.
Frédéric
F
Caupin
D003080:Cold Temperature; D003460:Crystallization; D007053:Ice; D008903:Minerals / Q000737:chemistry; D008956:Models, Chemical; D044367:Phase Transition; D010944:Plants / Q000737:chemistry; D011312:Pressure; D012542:Scattering, Radiation; D013227:Steam; D013314:Stress, Mechanical; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D007053:Ice; D008903:Minerals; D013227:Steam; D014867:Water
Berthelot tube; Widom line; scenarios for water