Study of the structural and atomic diffusive properties of the ordered Cu₃Au (110) surface

Abstract

The structural properties, the formation and migration energies of a single vacancy migrating intralayer and interlayer in the CuAu-terminated (110) surface of Cu 3 Au ordered alloy have been calculated and discussed by using the modified analytical embedded-atom method (MAEAM) and molecular dynamics (MD) methods. The surface layer exhibits rippling that the Au atoms are raised above Cu atoms about 0.117 Å in the topmost layer. The displacements of the topmost two layers are comparatively larger, while the third layer relaxes slightly and there are no changes in the nether layers. From energy minimization, the vacancy is most likely to be formed in the first layer (1L), especially on the Au site. The surface vacancy shows the smallest formation energy compared to the interlayer and bulk vacancies, while the corresponding value converges after the fifth layer (5L). For Cu vacancy originally sited in the second layer (2L) and migrated intralayer and interlayer, the diffusion without causing the local disorder is the most favorable, and the vacancy tends to migrate to the topmost layer. In the topmost layer of the CuAu-terminated (110) surface, the circularity path is preferred over the beeline path.