Structure of Amorphous Aluminium Oxide Films

Abstract

ALUMINIUM generally is covered with an oxide layer which gives excellent protection against corrosion. Preston and Bircumshaw¹ and other workers, using the electron diffraction method, showed that the layers are not crystalline. Their electron diffraction photographs show two diffuse rings which have not yet been explained satisfactorily. In air and at temperatures below the transition into the crystalline phase, the oxide layer grows very slowly, and only up to about 100 A. in thickness. Consequently, as the layer is too thin for X-ray methods, electron diffraction techniques have to be used.