Structural determination of amorphous NiTi thin films using electron diffraction analysis

Abstract

Structural analysis of amorphous Ni x Ti 1− x alloys ( x = 0.3–.07), obtained by vapor deposition, ion implantation and electron irradiation, has been made by electron diffraction techniques. Radial distribution functions (RDF) were derived from microdensitometer traces of diffraction patterns. From a simple fit routine, used to account for the decreasing width and position of the first RDF peak as the Ni concentration increases, it has been deduced that this first peak is the result of an overlap of two atomic coordination shells containing approximately 12 and 6 atoms, respectively; these coordination numbers are typical of a close packed structure. This may suggest that such atomic arrangements exist in the form of short range order in the amorphous structure. No major differences, in terms of peak positions and coordination numbers, were found between the structures of the amorphous NiTi alloys obtained by vapor deposition ion implatation and electron irradiation.