Manipulating ice crystallization of 0.9 wt. % NaCl aqueous solution by alternating current electric field

In this paper, we propose a physical method to manipulate the ice crystallization by applying an AC electric field during the liquid-solid transition of 0.9 wt. % NaCl aqueous solution. By using optical microscopic observation, we found that the ice grains are miniaturized in the presence of AC electric field during freezing process. Further study suggests that the grain size and the associated ice crystallization fraction are dependent on the field strength as well as frequency. And AC electric field can reduce the grain size and the crystallization fraction down to 35 μm and 71%, respectively, on the optimal condition (with field strength E = 100 kV/m, frequency f = 106 Hz). Moreover, the dielectric spectrum measurement of our sample close to transition temperature implies that such an optimal condition corresponds with a dielectric relaxation state, which might be the reason for the reduction of crystallized ice. Our finding may provide a potential way for cryoprotective application.