Fine structure of zr₈₀Pt₂₀ amorphous alloy determined from anomalous X-ray scattering (AXS) data by applying reverse monte-carlo (RMC) simulation method

The fine structure of a Zr₈₀Pt₂₀ amorphous alloy was evaluated by anomalous X-ray scattering (AXS) coupled with reverse Monte Carlo (RMC) simulation. Featureless short-range ordered structures were preferentially formed by the Zr component, similar to those described by dense random packing (DRP), while the Pt atoms adopted a somewhat different structure. The Pt atoms adopted Zr-rich coordination and an icosahedral local atomic arrangement, in unique chemical short-range ordering (CSRO) as well as topological short-range ordering (TSRO). The present AXS-RMC analysis also suggested that the pre-peak signal at 17 nm¹¹ in the X-ray diffraction profile was largely attributed to the correlation between the PtPt pair with a separation of approximately 0.40.5 nm. The geometrical and chemical features of the common neighbors of the middle-range PtPt pairs indicate the unique CSRO and TSRO, where both chemical and density fluctuations were observed in two distinct regions: a Zr-rich region with high packing density and a Pt-rich region with low packing density.