Effects of Polarity on Grain Boundary Migration in ZnO
Jong S. Lee, Sheldon M. Wiederhorn
Boundary migration of ZnO has been investigated using single crystals with defined crystallographic orientations. The migration rate of the basal C planes depended on the crystallographic polarity: Zn-terminated positive (0001)-planes. The migration in the non-polar directon was similar to that in the positive polarity direction. A ledge mechanism is suggested to be responsible for the grain boundary migration. These results explain the development of elongated grains in typical ZnO varistor ceramics.