Journal Article

Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials

Lavert, Etay, Ehre, David, Lahav, Meir, Lubomirsky, Igor

2010

Overview

Although ice melts and water freezes under equilibrium conditions at 0°C, water can be supercooled under homogeneous conditions in a clean environment down to -40°C without freezing. The influence of the electric field on the freezing temperature of supercooled water (electrofreezing) is of topical importance in the living and inanimate worlds. We report that positively charged surfaces of pyroelectric LiTaO₃ crystals and SrTiO₃ thin films promote ice nucleation, whereas the same surfaces when negatively charged reduce the freezing temperature. Accordingly, droplets of water cooled down on a negatively charged LiTaO₃ surface and remaining liquid at -11°C freeze immediately when this surface is heated to -8°C, as a result of the replacement of the negative surface charge by a positive one. Furthermore, powder x-ray diffraction studies demonstrated that the freezing on the positively charged surface starts at the solid/water interface, whereas on a negatively charged surface, ice nucleation starts at the air/water interface.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: air / Charging / Condensed matter: structure, mechanical and thermal properties / Cooling / Crystallography / Crystals / Diffraction / Droplets / electric field / Electric fields / Equations of state, phase equilibria, and phase transitions / Exact sciences and technology / Freezing / freezing point / Ice / ice nucleation / Liquids / melting / Melts / Molecules / Nucleation / Physics / Solid-liquid transitions / Specific phase transitions / Specimens / Surface temperature / Thin films / Water / Wave diffraction / X-ray diffraction