2020 Fiscal Year Research-status Report
Multiscale microstructure engineering and the development of high performance, environmental friendly, low cost and thermally stable half-Heusler thermoelectric materials
| Project/Area Number |
18K04744
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
蔡 耀汪 東京工業大学, 物質理工学院, 特任准教授 (80455922)
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| Co-Investigator(Kenkyū-buntansha) |
木村 好里 東京工業大学, 物質理工学院, 教授 (90262295)
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| Project Period (FY) |
2018-04-01 – 2022-03-31
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| Keywords | half-Heusler alloys / microstructure / interfacial structure / misfit dislocations / nanoprecipitates / thermoelectric / Ni-rich nanoclusters / atomic disorders |
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| Outline of Annual Research Achievements |
The research achievements in the current research are separated into two stages. The first one is that the interfacial microstructure in HH alloys can be modified by cyclic heat-treatment process around the critical decomposition temperature, so to significantly improve thermoelectric properties of the alloys. We anticipate the approach can be applied to many other TE material systems possessing with a miscibility gap system. The second stage of the research, which is still on-going, is centered on the development of HH alloys containing multiscale microstructure (including the microstructure mentioned above) to improve the TE performance more effectively. A paper submitted to the ACS Applied Materials & Interfaces was accepted on the 8th May 2021.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
The main reason is due to the lock-down imposed by the university, which is also inline with the Tokyo government. One in last year and another in this year.
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| Strategy for Future Research Activity |
Currently, a batch of HH alloys with varying amounts of V, Ta and Nb doping, has been fabricated by the directional solidification method. This method enables the production a multiscale microstructure half-Heusler thermoelectric alloys. Next, we will continue to
1) evaluate the thermoelectric properties of the as-grown and cyclic heat-treated alloys, and
2) investigate the multiscale microstructure (micro-scale, nanoscale and atomic scale) of the alloys by SEM, TEM, HRTEM, STEM and atomic probe tomography.
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| Causes of Carryover |
The main reason was due to lock-down by the Tokyo government and hence, the reduction activity in the university. These included cancellation of attending international conferences, working from home and reduced experimental activities in the university. In the next fiscal year, we plan to use the remaining research fund to support
1) the microstructure investigation of the alloy by using various electron microscopy techniques, such as SEM, TEM, HRTEM and STEM, and
2) the evaluation of thermoelectric properties of the as-grown and heat treated alloys at high temperature, such as specific heat (using differential scanning calorimetry) and thermal diffusivity (using laser flash).
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