Probing Bond Angle Orientations in CuZr Glass using Fluctuation X-ray Scattering and Angular Cross-Correlation*

Local orientational order is important for the thermodynamics of amorphous and liquid materials.  Most experiments characterize amorphous materials using the structure factor S(q), the Fourier Transform of the two-point density-density correlation function. Combining Fluctuation X-ray Scattering (FXS) and Angular Cross Correlation Analysis (ACCA) provides a quantitative framework for characterizing angular correlations. This study probes the bond angle orientations in a Cu₅₀Zr₅₀ glass. Diffraction patterns from the Cu₅₀Zr₅₀ glass samples were collected at the nano-focus beam line, ID13, at ESRF. The diffraction patterns were processed with an angular cross-correlation method based on the Martin et al. 2017, Pair Angle Distribution Function (PADF) analysis, enabling extraction of angular correlation functions in real space. The PADF analysis revealed significant correlations between bond angles, indicating preferred arrangements of atomic bonds and local structural motifs that are indicative of non-uniform structural configurations. These results highlight the power of combining advanced X ray scattering techniques and innovative data analysis methods to provide a more comprehensive description of the structural properties of amorphous materials and liquids.