Novel reconstructions of the (001) surface were observed directly by using high-resolution electron microscopy. The (001) surfaces which were obtained by  in situ  annealing under ultra-high vacuum conditions were found to exhibit a 2 x 1 structure at temperatures of less than about 200C. Such a surface transformed reversibly to a 3 x 1 structure at temperatures above 200C. It was suggested that the 2 x 1 reconstruction, stabilized by Cd atoms, consisted of half of a monolayer of Cd vacancies and a large inward relaxation of the remaining Cd surface atoms. The 3 x 1 reconstruction, stabilized by Te atoms, involved the formation of surface dimers and the presence of vacancies. In both reconstructions, atomic displacements were observed which extended a few layers into the bulk and served to reduce the strain energy.

P.Lu, D.J.Smith: Surface Science, 1991, 254[1-3], 119-24