Room-Temperature Ice in Electric Fields

Room-temperature ice is possible if the water molecules you’re freezing are submitted to a high enough electric field. Some physicists had predicted that water could be coaxed into freezing at fields around 10⁹ V/m. The fields are thought to trigger the formation of ordered hydrogen bonding needed for crystallization. Now, for the first time, such freezing has been observed, in the lab of Heon Kang at Seoul National University in Korea, at room temperature and at a much lower field than was expected, only 10⁶ V/m. Exploring a new freezing mechanism should lead to additional insights about ice formation in various natural settings, Kang believes (surfion@snu.ac.kr).

The field-assisted room-temperature freezing took place in cramped quarters: the water molecules were constrained to the essentially 2-dimensional enclosure between two surfaces: a gold substrate and the gold tip of a scanning tunneling microscope (STM). Nevertheless, the experimental conditions in this case, modest electric field and narrow spatial gap, might occur in nature. Fields of the size of 10⁶ V/m are, for example, are thought to exist in thunderclouds, in some tiny rock crevices, and in certain nanometer electrical devices. (Choi et al., Physical Review Letters, 19 August 2005; for another example of seemingly room-temperature ice, see PNU 225)