Electric Charge Can Change Freezing Point of Water

[P]revious experiments to understand whether electric fields can influence freezing were complicated by the materials used. The best materials for holding electric charge are metals, but as anyone who has tried to open a car door after a snowstorm knows, ice forms easily on metals even without a charge.

“If you try to do it with metal, you don’t know what is from the electric field and what is from the metal itself,” Lubomirsky says. “We wanted to know whether it is the charge that does it, or something special in metal.”

Instead of metal, Lubomirsky and his colleagues used a pyroelectric material, which can form a short-lived electric field when heated or cooled. The researchers used four pyroelectric crystals, each of which was placed inside a copper cylinder. The bottom surfaces of two crystals were coated with chromium to conduct an electric charge, and the other two were coated with an aluminum oxide to keep the surface uncharged.

An obvious question, not addressed by the article, is why you couldn’t (or rather, why they didn’t) create an external field separate from the surface being used for the condensation and freezing, and see how that affected the freezing point. This doesn’t seem to differentiate between surface and bulk effects.