With increasing annealing temperature, Auger electron spectroscopy (AES) of a Cr(100) single crystal shows segregation of C, N and O as dominating segregating species, indicating competitive segregation of these elements. An STM study of N structures shows a c(2x2) superstructure at N coverages up to 1/2. The local N coverage can be increased by insertion of N-rich domain boundaries up to 2/3, where a c(3√2 × √2)R±45° structure forms; followed by a first-order phase transformation to a p(1x1) structure. The existence of patches of the N-rich p(1x1) structure at coverages below 2/3 is probably due to additional carbon impurities stabilizing this structure. The possibility of inverse corrugation on the pure Cr(100) surface is discussed.
Corresponding author: M. Schmid (schmid).
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