X-ray Diffraction Study of the Ultrathin Al 2 O 3 Layer on NiAl(110)

Abstract

Ultrathin Al 2 O 3 layers on alloys are used as templates for model catalysts, tunneling barriers in electronic devices, or corrosion-resistant layers. The complex atomic structure of well-ordered alumina overlayers on NiAl(110) was solved by surface x-ray diffraction. The oxide layer is composed of a double layer of strongly distorted hexagonal oxygen ions that hosts aluminum ions on both octahedral and tetrahedral sites with equal probability. The alumina overlayer exhibits a domain structure that can be related to characteristic growth defects and is generated during the growth of a hexagonally ordered overlayer (Al 2 O 3 ) on a body-centered cubic (110) substrate (NiAl).