Polarization phenomena induced by cracks in Ih ice crystals

Summary  In single and polycrystals of «pure» Ih ice, large cracks were mechanically produced along prismatic planes; at the same time large potential changes (up to 40 volt) were measured on the surface of the sample. The decay of the potential observed under isothermal and constant warming rate conditions led to the hypothesis of a polarization associated with a dislocation motion activated by Bjerrum defects. The activation energy found ((0.20 ± 0.02) eV) is close to the values reported in the literature for the migration of these defects. It is pointed out that such a phenomenon may take part in thunderstorm electrification.