2023 Fiscal Year Research-status Report
Accurate site-selective atomic structure determination by single-energy x-ray holography
| Project/Area Number |
20K15027
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2025-03-31
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| Keywords | x-ray holography / site-selectivity / local atomic structure / local disorder |
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| Outline of Annual Research Achievements |
New advances in methods using x-ray fluorescence holography (XFH) have the potential to become a universal tool for site-selective investigations in crystals. These methods combine the intrinsic element-selectivity of XFH with the possibility for a chemical characterization of the environment. This is achieved by a resonant approach, i.e. tuning the x-ray energy to an energy that coincides with an x-ray absorption edge in the material.
The proposed project aims to practically implement such site-selective measurements and to apply them to current research issues in materials science. This approach is useful for, among else, identifying local atomic environments with chemical information and for understanding in detail the chemical disorder. One of the obstacles here is the atomic image cancellation effect, which leads to a large decrease in the signal intensity of certain pairs of distances and incident energies.
In this FY, the investigation using resonant XFH of a short-range-ordered Ni-Fe alloy was advanced. Furthermore, we investigated computationally the effect of various kinds of disorder on the holographic data to establish a reference for future experimental works. This approach was also employed to compare the data about local atomic disorder from holographic techniques with those from established methods like Diffuse Scattering. The XFH data are found to complement existing information well due to its site-selective properties.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The project is progressing smoothly. Experiments at large-scale research facilities were conducted as planned, and another 2 experiments for FY 2024 are already approved.
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| Strategy for Future Research Activity |
In the further course of this research, it is planned to apply the insight gathered so far for a complex functional material, which is a High Entropy Alloy consisting of 6 principal elements. The site-selective investigations developed here can significantly push forward the current knowledge about the structure of these highly topical material system. In particular, it will be interesting to investigate whether short-range atomic order exists between specific elements, which can have a major impact on the material properties.
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| Causes of Carryover |
The remaining budget will be used for finishing the last experiments at large research facilities and the corresponding travel expenses, as well as for presentation of the scientific results of this project at international conferences.
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