Atomic structure of a {001} surface of Ni3Al

A low-energy electron diffraction intensity analysis of a clean Ni3Al{001} surface confirms the mixed-layer (50% Ni50% Al) termination of this surface and reveals a small contraction of 2.8% of the first interlayer spacing (bulk value 1.78 A), with the Al atoms slightly farther out (0.020.03 A) than the Ni atoms, while the second interlayer spacing is bulklike. © 1986 The American Physical Society.