Local-order hypotheses and atomic arrangement in the glassy alloy As0.45Se0.05Te0.50 by X-ray diffraction

Abstract

The radial atomic distribution of the amorphous alloy As0.45Se0.05Te0.50 was studied through the X-ray diffraction data supplied by samples obtained through quenching. The short-range order was determined by interpreting the radial distribution function (RDF), using a theoretical expression which takes into account the variation in the atomic scattering factors withs (the scattering vector module), and approximates them to polynomic functions. The tetra- and tri-coordinated arsenic hypotheses, quoted in the literature for glassy alloys containing this element, were considered. The result of the study is that, for the alloy in question, only the tri-coordinated arsenic hypothesis is compatible with the structural information that was experimentally obtained. A spatial atomic distribution model was generated according to this arsenic coordination, using the conveniently modified Monte Carlo random method. The model is a network of triangular pyramids with arsenic atoms at some vertices. A comparative analysis of the main structural parameters of this model revealed their good agreement with the values given in the literature for similar alloys.