NaCl(001) surfaces nanostructured by Suzuki precipitates: a scanning force microscopy study

Suzuki precipitates on the (001) surfaces of as-cleaved and additionally annealed NaCl: Cd2+ crystals were studied by means of dynamic scanning force microscopy and Kelvin probe force microscopy in ultra-high vacuum. Rectangular precipitates with edge lengths of up to several hundred nanometres can be found on the surfaces of as-cleaved crystals. The precipitates exhibit steps, which are a result of the cleavage of dislocations at the Suzuki-NaCl interfaces. Additional annealing of the crystals below 260 degrees C leads to surface diffusion and to a restructuring of the whole surface producing atomically flat precipitates at steps, but also on flat terraces in regions of low step density. On surfaces evaporated at 350 degrees C, the main surface characteristics of evaporated (001) surfaces of pure NaCl can be found. The step edges are merely changed in shape by nanometre-size Suzuki precipitates.