In situtransformation of amorphous ices at high pressures

By using thermal conductivity and its change with temperature and pressure as a criteria for in situ structural transformation of the crystalline and amorphous solid forms of water, we report two findings: (i) transformation of high-density amorph (HDA) directly to cubic ice on slow depressurization and (ii) slow transformation or dilation of metastable HDA at 1300.3em0exK to a low-density amorph (LDA) even when the pressure was increased from 0.20.3em0exto0.3em0ex0.30.3em0exGPa, and then gradual reversion by collapse of the LDA to HDA on further pressurization to 0.50.3em0exGPa. We also discuss implications of these findings for the current understanding of the transformations of metastable ices under pressure, particularly of those studied in situ.