For centuries water has been known to have many highly anomalous physical properties, and amorphous solid ice continues to attract significant debate.High density amorphous (HDA) ice is a form of solid water produced by compression of ice to 11 kbar below 130 K. Amorphous ice has not been observed to recrystallize while being stored in liquid nitrogen, and it seems that once formed and kept at low temperature, it is kinetically stable indefinitely. However, the amorphous form is not the lowest energy state, these states are likely to be proton ordered crystalline forms that have a degree of either ferroelectric or anti-ferroelectric ordering of the water dipoles. The most recent work involves pressurization of ice into the higher temperature ‘no-man’s-land’ regime (between 145 K and 200 K) and shows that indeed the kinetics are such that the crystalline phases can result. Here we show that in the region of typical HDA formation (100 K) pressurization of pure ice I results in a series of crystalline phases, starting with the formation of proton ordered but non-interpenetrating ice IX’, then proton ordered and interpenetrating ice XV’, and finally ice VIII’. During fast compression HDA results, when ice IX is passed over, and a fully completed single step transformation between ice I and ice XV’ is inhibited. Thus, the formation of high density amorphous ice appears to be an artifact of a kinetically arrested transformation between low density ice I and high density anti-ferroelectrically ordered ice XV’. This result shows the equilibrium crystallographic transitions of ice at low temperature, ‘normalizes’ some of the perceived exotic behavior of water and questions the current theory of amorphous ice and its relation to supercooled liquid water. [1]

[1] Chris A. Tulk, Jamie J. Molaison, Adam Makhluf, Craig Manning, Dennis D. Klug, Nature, 569, 542–545 (May 2019).