A scanning tunnelling microscopic study was made of the ordered alloy. The (111) surface exhibited a bulk terminated p(2 x 2) structure or a (v3 x v3)R30º reconstruction; depending upon the preparation conditions. The reconstructed surface also exhibited a mesoscopic honeycomb network. The mean width of these features was about 15nm, with a height of 0.06 to 0.07nm. This network indicated the presence of sub-surface dislocations, which were introduced by Sn depletion due to preferential sputtering. Small islands of uniform size were found on the p(2 x 2) structure, and were attributed to segregated Sn. It was concluded that, since the bulk-truncated p(2 x 2) structure developed via the Sn-enriched (v3 x v3)R30º phase, excess Sn atoms had either to be incorporated into sub-surface layers or be pushed out of the surface to form adatoms. In the latter case, the expected adatom concentration would be of the order of 1/12 of a monolayer. This seemed to be higher than the observed concentration. Incorporation into sub-surface layers was therefore supposed to be the main mechanism which reduced the Sn concentration in the top layer. The boundary between the p(2 x 2) and (v3 x v3)R30º domains was very sharp. Nucleation of the p(2 x 2) domains began in the center of the meshes which formed the honeycomb network. This was repeatedly observed after annealing at 800K.

Reconstruction and Dislocation Network Formation of the (111) Surface of the Ordered Alloy Pt3Sn. J.Kuntze, S.Speller, W.Heiland, A.Atrei, I.Spolveri, U.Bardi: Physical Review B, 1998, 58[24], R16005-8