Anomalous thermodynamic properties of ice XVI and metastable hydrates

Last update: March 1, 2016

A paper is published in Phys. Rev. B.  


T. Yagasaki, M. Matsumoto, and H. Tanaka,  Phys. Rev. B 93, 054118 (2016).


Water is known to be an "anomalous liquid", i.e., the solid state floats on the liquid state.  It is also well known that water expands when it is cooled below 4°C.  While, water has another interesting anomalous property, in which crystal ice also expands when it is deeply cooled below 55 K.


In this research, we elucidated the mechanism of the negative thermal expansivity of ice I (normal ice) and ice XVI (recently discovered low-density phase of ice), and explained why this anomaly disappears in the gas hydrates that has the same skeletal structure with ice XVI.  We also proposed the way to produce a new kind of metastable gas clathrate by applying the method to make ice XVI.