Tilt grain boundary energy in 〈0001〉/φ bicrystals of pure ice

Abstract

This work presents measurements of the relative energy ( γgb/ γs) of the tilt grain boundary (GB) in pure ice bicrystals with crystalline misorientation 〈0001〉/ φ. The GBs had different inclinations and were annealed at −5 °C and −18 °C. A GB structure model called the facet model (FM) was applied. The FM assumes that the GB is composed of facets. The facets are oriented with the principal faces of the cell primitive of the coincident site lattice (CSL). The CSL is associated with the bicrystalline misorientation. In general, ( γgb/ γs) varies by more than one order of magnitude between temperatures −5 °C ( γgb/ γs ~ 0.03) and −18 °C ( γgb/ γs ~ 0.35), so GB structural changes are very noticeable with temperature. The GB energy does not depend on the inclination at temperatures near 0 °C, while the dependence on inclination presents a slight significance at −18 °C. Finally, it was observed that the GB relative energy ( γgb/ γs) for bicrystalline 〈0001〉/ φ samples is lower than the relative energy at other crystalline misorientations. These experimental data are unique and could explain the slow GB migration in 〈0001〉/ φ bicrystals and they could help to understand grain growth in polar ice where the most frequent crystalline misorientation is 〈0001〉/ φ.