Volume of supercooled water under pressure and the liquid-liquid critical point

The volume of water (H2O) was obtained at about 200-275 K and 40-400 MPa by using emulsified water. The plot of volume against temperature showed slightly concave-downward curvature at pressures higher than approximate to 200 MPa. This is compatible with the liquid-liquid critical-point hypothesis, but hardly with the singularity-free scenario. When the critical point is assumed to exist at approximate to 50 MPa and approximate to 223 K, the experimental volume and the derived compressibility are qualitatively described by the modified Fuentevilla-Anisimov scaling equation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3487999]