First-principles sliding simulation of Al-terminated Σ13 pyramidal twin grain boundary in α-Al₂O₃

First principles plane wave basis calculations were performed to investigate the atomic-scale mechanism of grain boundary (GB) sliding of the Al-terminated Σ13 pyramidal twin GB in α-Al₂O₃ in order to investigate the difference in sliding properties from the previously reported result of O-terminated GB. Atomistic mechanism of sliding process was found to be similar to the previously reported O-terminated GB, that is, the sliding takes place with successive breaking/rebonding of Al-O bonds across the GB core [Nakamura et al., Phys. Rev. B 75 (2007) p.184109]. On the other hand, it was found that sliding resistance of the Al-terminated GB is higher than that of the O-terminated one, though they have the identical orientation relationship. Quantitative chemical bonding analyses show that the difference in the sliding resistance originates from the local Al-O bonding characteristics of individual Al-O pairs across the GB plane.