Inelastic properties of several high pressure crystalline phases of H2O: Ices II, III, and V

We have performed deformation experiments on cylinders of polycrystalline H₂O at temperatures from 178 to 257 K at pressures to 500 MPa in the stability fields of ices II, III, and V. Ice II is the strongest of the phases, having a strength under laboratory conditions roughly comparable to that of ice I_h. Ice V is somewhat weaker than ice II. Ice III is extremely weak and over geologic times must behave essentially as a liquid bounded below by ice V and above by ice II or I_h. Phase relationships are complicated by a number of phase metastabilities, the most important of which is the existence of ice III in the ice II field for extended periods of time. Even under deformation at temperatures as low as 211 K (over 30 K below the ice III field), the transformations from III to II can not be made to happen in the laboratory.