A STUDY OF SHORT-RANGE ORDER AND ATOMIC ARRANGEMENT IN THE GLASSY ALLOY CU0.03GE0.20TE0.77 BY X-RAY-DIFFRACTION

The radial atomic distribution of the amorphous alloy Cu0.03Ge0.20Te0.77 was studied using 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 that takes into account the variation in the atomic scattering factors with s (the scattering vector module) and approximates them to polynomic functions. The tetra- and dicoordinated-copper 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 tetracoordinated-copper hypothesis is compatible with the structural information that was obtained experimentally. A spatial atomic distribution model was generated in accord with this copper coordination, using a conveniently modified Monte Carlo (random) method. A comparative analysis of the main structural parameters of this model revealed good agreement with the values given in the literature for similar alloys.