Synthetic [100] tilt grain boundaries in forsterite: 9.9 to 21.5°

Pure forsterite bicrystals were produced by direct bonding of highly polished single crystal plates. We fabricated a series of synthetic grain boundaries with tilt axis a and tilt angles ranging from 9.9 to 21.5°. Transmission Electron Microscope (TEM) investigations show low-angle grain boundaries with arrays of c-dislocations for all misorientations with tilt angles up to 21.5°. Low-angle grain boundary structures were fully developed at annealing temperatures <400°C and no structural changes were observed in the grain boundary region after further annealing at 1650°C.