Room-temperature scanning tunnelling microscopic images of the (001) surface revealed the pinning of small domains of c(4 x 2) and p(2 x 2) superstructures by defects and contaminants. This confirmed surface X-ray diffraction results concerning limits on the c(4 x 2) domain size on his surface when below the order-disorder phase transition temperature. An improvement in the domain size was possible by using different preparation techniques.

S.J.Murray, M.Mian, F.M.Leibsle, R.McGrath: Surface Science, 1994, 307-309, 741-6