Surface-induced disorder on the cleanNi3Al(111)surface

Abstract

The structure of the clean Ni3Al(111) surface has been studied using surface x-ray diffraction. Analysis of the crystal truncation rods reveals that the clean surface contains an unexpected disorder while the bulk remains ordered. This surface-induced disorder extends down to the sixth layer and it decreases gradually with depth. The surface is, on the whole, stoichiometric and the maximum deviation per layer from the ideal 3Ni:1Al composition is less than 8\%. There is a very small difference (0.02±0.01A) between the relaxations of the two different sites at the surface, and the interlayer distance between the outmost, second, and third layers is slightly reduced (0.02±0.01A) with respect to the bulk value.