Studies were made, of surface changes which occurred during the annealing of (001), by using scanning tunnelling microscopy. Transitions from ordered (2 x 4)/c(2 x 8) reconstructed surfaces, to an ordered mixed phase (2 x 6)/(3 x 6) reconstruction, was observed as the vacuum annealing temperature was increased from 450 to 500C. The transition to the high-temperature phase was mediated by a transient disordered state. At vacuum annealing temperatures of about 520C, it was found that terrace edges in the (2 x 6)/(3 x 6) phase became unstable and that the surface changed to a morphology which was similar to those which were observed in general pattern-forming systems. A mechanism which was based upon the diffusion-limited growth of surface vacancies was considered.

C.W.Snyder, J.Sudijono, C.H.Lam, M.D.Johnson, B.G.Orr: Physical Review B, 1994, 50[24], 18194-9