Comparing In-House and Synchrotron 3D-ΔPDF Analysis of Correlated Disorder in Crystals

What is it about?

This research compares the measurement of diffuse scattering data and subsequent three-dimensional difference pair-distribution function (3D-ΔPDF) analysis of correlated disorder in crystals using both in-house X-ray sources and synchrotron radiation. The study evaluates data quality and structural insights by analyzing identical crystal specimens of Cu₁.₉₅Se, Nb₁−ₓCoSb, and InTe with both instrument types. Methodologically, the 3D-ΔPDF approach is applied to single crystals, exploiting its ability to highlight deviations from the average structure by removing Bragg peak contributions and enhancing contrast for local disorder analysis. The article finds that, while in-house measurements yield qualitatively similar 3D-ΔPDF features to synchrotron data, they suffer from lower signal-to-noise ratios, radial peak broadening due to non-monochromatic radiation, and limited Q-space coverage. For Cu₁.₉₅Se and Nb₁−ₓCoSb, in-house data permitted meaningful disorder analysis, albeit with additional considerations for noise and integration parameters. In contrast, for InTe, the weaker diffuse signal and broader peaks impeded construction of a full disorder model using in-house data. Overall, the study concludes that in-house 3D-ΔPDF analysis is effective for many correlated disorder studies, but synchrotron data provide superior resolution and accuracy for detailed structural characterization.

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Photo by Egor Komarov on Unsplash

Photo by Egor Komarov on Unsplash

Why is it important?

This research directly compares the capabilities of in-house and synchrotron X-ray sources for measuring diffuse scattering and conducting three-dimensional difference pair-distribution function (3D-ΔPDF) analysis of correlated disorder in single crystals. The findings are relevant to the field of crystallography, where understanding local structural disorder is essential for the development and characterization of functional materials such as thermoelectrics, battery materials, and frameworks for information storage. Key Takeaways: 1. The study demonstrates that in-house 3D-ΔPDF measurements are effective for analyzing correlated disorder in single crystals, showing comparable qualitative insights to synchrotron-based measurements for certain materials, such as Cu₁.₉₅Se and Nb₁−ₓCoSb. 2. Findings reveal that in-house sources generally exhibit lower signal-to-noise ratios and radial peak broadening due to non-monochromatic radiation, which can limit the resolution and the ability to construct detailed structural models—especially for materials with weak diffuse scattering, as observed in the case of InTe. 3. The research highlights that while in-house methods increase accessibility and flexibility for diffuse scattering studies, synchrotron sources remain superior in providing higher data resolution and better signal-to-noise ratios, leading to more accurate and detailed analyses of crystal structures.