Insight into the phase transformations between ice Ih and ice II from electron backscatter diffraction data

Electron backscatter diffraction data from polycrystalline water ice, cycled three times through the 1h to II phase transformation, show that an area equivalent to the original grain size (∼450 μm) now comprises equant 10 μm grains with a non-random crystallographic preferred orientation (CPO). Pole figures show small-circle ring and fence patterns characteristic of CPO development controlled by an orientation relationship during phase transformation. Misorientation analysis shows that one of two orientation relationships can explain the data:<0 0 0 1>1h/<1 0-1 0>II, {1 0-1 0}1h/{0 0 0 1}II or <0 0 0 1>1h/<1 1-2 0>II, {1 0-1 0}1h/{0 0 0 1}II.