Atomic structure of alloy surfaces. II.Ni3Al{111}

A low-energy-electron-diffraction intensity analysis of a clean ${\mathrm{Ni}}_3$Al{111} surface reveals a structure that is essentially bulklike, but with a slight buckling of the first atomic layer. The plane of the Al atoms is moved outwards to a position 0.06±0.03 Å from the plane of the Ni atoms, which is in turn very slightly shifted inward (0.01±0.03 Å) toward the second atomic layer. Second and deeper interlayer spacings are expected to be equal to the bulk value (2.055 Å). The r-factor values for both normal (0.13) and oblique (0.16) incidence correspond to a very good fit of theory to experiment.