Techniques for determining pressure in the hydrothermal diamond- anvil cell: behavior and identification of ice polymorphs (I, III, V, VI)

For H2O densities > 1.0 g/cm3, a determination of the ice melting temperature provides the density information required to calculate the P-T path that the sample in a hydrothermal diamond-anvil cell follows when the sample is heated isochorically. The principal difficulty is the identification of the polymorph because of metastable behavior of ices in the H2O system. Usually, an accurate identification of the liquidus ice phase can be made without analytical instrumentation and requires only careful observations. -Authors