Equivalent ordered-mixed-surface-structures of p(4 × 4)-p4gm formed on Cu(0 0 1) by coadsorptions of Bi + Mg and Sb + Mg

Two coadsorption systems of Bi + Mg and Sb + Mg on Cu(0 0 1) have been studied by means of low-energy electron diffraction (LEED). A (4 × 4) LEED pattern with glide planes was observed in either case at ∼400 K. The two (4 × 4) structures were determined by a tensor LEED analysis. Both (4 × 4) structures are equivalent, and consist of a grid network of Mg2Bi2 (Mg2Sb2) plane clusters on a partially Bi (Sb) substituted Cu(0 0 1) layer. Structural parameters show that not only the formation of the clusters but also the arrangement of the clusters into the grid network contributes to the stabilization of this ordered-mixed-surface-structure.