Temperature dependence of "pure" ice grain boundary mobility

Pure ice bicrystals with crystalline misorientation (left angle bracket)1 0 1 0(right angle bracket)/60° and different configurations were prepared using Milli Q water (impurities less than 10-2 ppm) and annealed at -5, -10, -15 and -20 °C for 170 days. The grain boundary migration was analyzed using a theory developed for the migration of a grain boundary interacting with the sample surface. For each temperature, two samples were measured and grain boundary mobilities were determined. It is observed that the obtained values are widely dispersed, but their maximums can be accurately fitted by an Arrhenius law with an activation energy of 0.53 eV. The experimental values of grain boundary mobility obtained are compared with the theory. It is shown that, for the study temperatures, grain boundaries in "pure" ice do not behave as a liquid-like structure.