Electronic structure of NiAl

Abstract

The valence-band structure of nickel aluminum was measured by use of angle-resolved photoemission with synchrotron radiation and calculated using the local-density approximation. The overall agreement between theory and experiment is remarkably goodmuch better than for pure nickel. This means that the "self-energy" corrections are significantly less in NiA1 than in pure nickel. The core-level binding energies in NiAl are compared experimentally and theoretically with the equivalent levels in Ni and Al. Surprisingly, the Ni core shifts to higher binding energy and the Al to lower as if charge were transferred from Ni to Alopposite to the direction predicted from electronegativity. These observations are discussed in terms of bonding in NiA1. 42 1582 1990 The American Physical Society 42 ELECTRONIC STRUCTURE OF NiAl 1583 from Ni to Al), leading to a net transfer from nickel to aluminum.This is consistent with the observed corelevel shifts, which are in the direction of larger binding energy for the nickel and smaller binding energy for the aluminum. Shifts to the lower binding energy are usually attributed to an increase in electron number at a site which increases the Coulomb repulsion with the cores and reduces the binding energy.

Preparation dependent surface structure of NiAl(100)

“…The STM simulation produced correlates with the STM data, and can be described as the Ni density of states (DOS) dominating at the surface, producing the defined row structure as described above. DOS calculations confirm a dominant Ni d band within NiAl [15].…”

Angular distributions of atoms sputtered from NiAl{110} and Ni{100}

“…The efficiency of energy transfer is much lower in Ni-Al collisions than that in Ni-Ni collisions. In the bcc NiAl single crystal alloy, an Al atom is enclosed by Ni atoms [18]. The collisions along h1 0 0i lattice directions in the NiAl single crystal alloy are Ni-Ni collisions, while the collisions along the h1 1 1i crystal directions are either Ni-Al or AlNi collisions, so energy transfer is minimized.…”

Surface electronic structure of Ti-based transition metal alloys

“…[30][31][32][33][34] Our calculation shows that a five-layer slab already reproduces the surface and bulk region quite well. We would like to emphasize that the surface effects are confined mainly to the surface layer in the case of the ͑110͒ surface, and do not spread into solid ͑top panel in Fig.…”

“…24 -29 The ͑001͒ and ͑110͒ surfaces were studied very intensively for B2 NiAl alloy. [30][31][32][33][34] The knowledge of surface electronic structure for transition metal alloys is also important for understanding the martensitic transformations at the surface, which can be different from those in the bulk. Adsorption on the ordered transition metal surfaces is a rather unexplored field yet.…”