Unusual Phase Behavior of Confined Heavy Water
Abstract
Many of the anomalous properties of water are amplified in the deeply supercooled region. Here we present neutron scattering measurements of the density of heavy water confined in a nanoporous silica matrix MCM41S (\approx15 Å pore diameter), namely, the equation of state {\rho}(T,P), in a temperaturepressure range, from 300 K to 130 K and from 1 bar to 2900 bar, where bulk water will crystalize. A sudden change of slope in the otherwise continuous density profile (a "kink") is observed below a certain pressure Pc; however, this feature is absent above Pc. Instead, a hysteresis phenomenon in the density profiles between the warming and cooling scans becomes prominent above Pc. Hence, the data can be interpreted as a line of apparent 2ndorder phase transition at low pressures evolving into a line of 1storder phase transition at high pressures. If so, the existence of a "tricritical point" at Pc \approx 1500 bar, Tc \approx 210 K becomes another possible scenario to explain the exceptionally rich phase behavior of lowtemperature confined water.
 Publication:

arXiv eprints
 Pub Date:
 May 2010
 DOI:
 10.48550/arXiv.1005.5387
 arXiv:
 arXiv:1005.5387
 Bibcode:
 2010arXiv1005.5387Z
 Keywords:

 Condensed Matter  Soft Condensed Matter;
 Condensed Matter  Disordered Systems and Neural Networks;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Statistical Mechanics
 EPrint:
 15 pages, 4 figures