2020 Fiscal Year Annual Research Report
Direct local structure determination of quasicrystals in physical space
Publicly Offered Research
| Project Area | Hypermaterials: Inovation of materials scinece in hyper space |
|---|
| Project/Area Number |
20H05273
|
|---|
| Research Institution | Hiroshima University |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2020-04-01 – 2022-03-31
|
| Keywords | Hypermaterials / Atomic structure / X-ray holography / local structure / quasicrystal |
|---|
| Outline of Annual Research Achievements |
This project contributed to the understanding of complex atomic arrangements of hypermaterials using atomic-resolution X-ray holography. This method circumvents the phase problem of traditional crystallography, thus providing unique 3-dimensional structure information in a direct manner (i.e. without the need for an a-priori model or data refinement). It represents new way to visualize intricate aperiodic structures with an element-selective approach and to support existing models with complementary experimental data (in addition to e.g. superspace crystallography approaches).
The experiments using large-scale synchrotron facilities were performed for several decagonal and icosahedral quasi-crystalline systems. The data could be interpreted as 3-dimensional local pair distribution functions in the range of about 2 nm around a specific element. These features represent distinct advantages in contrast to comparable methods aimed at local structure characterization like X-ray absorption spectroscopy. It could also be demonstrated that the 3D data also indicate distinct structural features, for example the connectivity between the icosahedral clusters, which are difficult to determine by traditional crystallographic and spectroscopic approaches.
Furthermore, a new detecting system was introduced in the previous fiscal year, which uses a 2-dimensional area detector. With this system, a wide variety of target elements is now feasible for measurement.
|
| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Even despite several delays regarding experimental plans (due to the travel restrictions caused by the pandemic), the aims of the project were achieved and even surpassed.
Regarding the original project plan, a new detecting system using a 2-dimensional detector was successfully introduced, which possesses an excellent performance especially for the more challenging high-energy applications. Furthermore, experiments for reference samples of decagonal and icosahedral quasi-crystalline systems were successfully performed, and the theoretical groundwork for the interpretation of the data was established.
Beyond the original plan, we started measurements of a novel type of icosahedral systems with the composition Cd-Mg-Tb, in collaboration with a research group at the IMR (Tohoku University).
|
| Strategy for Future Research Activity |
In the ongoing research, the description of the local structure of especially icosahedral systems will be developed further, for example by comparison with detailed computational modelling of specific atomic environments. Moreover, in the future, the experimental and analytical methods developed in this project will be extended particularly to low-temperature and nano-focus applications. This will greatly widen the range of application of the experimental method to most quasi-crystalline systems that are interesting for state-of-the-art research. In particular, by using a quantitative approach of ARH, it will be possible to study the relationship between local distortions and material properties (in particular regarding magnetic effects).
Integrated with complementary material characterizations, the expected results will be able enable a whole new perspective for the understanding of the structure-property relationships in the studied materials.
|
