Grain-boundary grooving experiments were performed on Σ5 (210) twist boundaries. Planar boundaries, oriented 90° to the surface, were annealed in air using various times and temperatures. Atomic force microscopy was used to characterize the resultant grooves. Use of the Mullins approach led to the expression:

D (m2/s) = 3.9 x 10-10 exp[-330(kJ/mol)/RT]

This relatively low activation energy agreed well with previous O tracer diffusion measurements; thus suggesting that O was the limiting diffusing species in the boundary grooving.

Grain Boundary Grooving Studies of Yttrium Aluminum Garnet (YAG) Bicrystals. M.I.Peters, I.E.Reimanis: Journal of the American Ceramic Society, 2003, 86[5], 870-6