2018 Fiscal Year Annual Research Report
A preparation and optical property study of Nanostructured-Metal Materials
| Project/Area Number |
17F17793
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| Research Institution | Tohoku University |
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Principal Investigator |
渡辺 健太郎 東北大学, 材料科学高等研究所, 准教授 (40582078)
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| Co-Investigator(Kenkyū-buntansha) |
XIA YANJIE 東北大学, 材料科学高等研究所, 外国人特別研究員
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| Project Period (FY) |
2017-11-10 – 2020-03-31
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| Keywords | Vapor Phase Dealloying / Nanoporous Metal |
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| Outline of Annual Research Achievements |
Wrinkled nanoporous metal with 3D bicontinuous structures are emerging as a new class of functional and structural materials for a wide range of applications, including plasmonics for optical property enhancement. For this plasmonic application, it is crutial to control microstructural parameters of 3D bicontinuous nanoporous metals, such as pore size, pore depth, and porosity.
Vapor phase dealloying (VPD) is expected as a universal, highly efficient and environmentally friendly method for fabricating 3D bicontinuous nanoporous metals, by using vapor pressure difference between constituent elements. However, the relation between dealloying conditions and above microstructural parameters are still unclear due to underlying dealloying kinetics, such as thermal evaporation of constituent element, resulting diffusion both in bulk alloys and in pore channels, and alloys phase evolution. In this work, 3D bicontinuous nanoporous Cu by VPD of Cu12Zn88 alloy is chosen as the model system and its dealloying kinetics and alloy phase evolution are investigated.
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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
In FY2018, we found that Zn is selectively evaporated out from the precursor Cu12Zn88 alloy during the process of VPD due to the vapor pressure difference between Cu and Zn and an intermediate phase Cu36Zn64 is formed in the dealloying front before Zn evaporation. The power law relation between the pore depth and dealloying time reveals the bulk diffusion controlled dealloying process for intermediate phase. The porous structure starts to appear in the intermediate region and the appearance time closely relies on dealloying temperature. The constant dealloying front velocity is mainly dominated by dealloying temperature and slightly increased in high vacuum condition, indicating that the dealloying kinetics is dominated by interfacial effect rather than mass transport effect in pore channel. The two-step dealloying process and the linear dealloying kinetics in nanoporous region provide a new insight for understanding the dealloying process and phase evolution by VPD.
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| Strategy for Future Research Activity |
Our future work contains the followings.
(1) VPD experiment and data analysis, including VPD of CuZn alloys at different compositions and VPD under different dealloying conditions.
(2) Understanding VPD mechanism by proposing its physical model.
These study will be summarized in a manuscript for publication.
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Research Products
(2 results)
