Achieving thermal conductivity reduction of phononic crystals through deepening the transport theory of phonon waves
| Project/Area Number |
18J14024
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Single-year Grants |
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| Section | 国内 |
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| Research Field |
Thermal engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
LIAO YUXUAN 東京大学, 工学系研究科, 特別研究員(PD)
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| Project Period (FY) |
2018-04-25 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2019: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2018: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Thermal conductivity / Coherent transport / Incoherent transport / Crystal phononic crystal / Amorphous phononic / coherence / phonon / thermal conductivity / phononic crystals / Ahkhizer damping |
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| Outline of Annual Research Achievements |
The ability to control the thermal conductivity of semiconductors and insulators, either crystal or amorphous, is of crucial importance to determine the functionality and usability of the material used in a wide range of applications such as thermoelectrics, thermal barriers and thermal insulators. The applicant has investigated fundamental mechanisms of coherent and incoherent transport related to the ways of reducing the thermal conductivity of the material with phononic structures. The applicant showed that coherent effect is not significant in both crystal and amorphous phononic materials due to Akhiezer damping, which significantly reduces relaxation time of coherent phonons. The applicant along with his collaborators showed that local elastic modulus softening can not only significantly reduce the thermal conductivity of crystal phononic materials by reducing phonon group velocity, but also play an important role to achieve huge thermal reductions in nanocomposite via large limitation of phonon transmittance at the interfaces of the nanograins. The applicant showed that boundaries in amorphous phononic materials and superlattice can not only strongly scatter phonon-like propagons, but also exhibit extremely scattering of diffusons such that the thermal conductivity is below the diffusive limit of amorphous. These works have deepened the physical understanding of both coherent and incoherent transport in crystal and amorphous phononic materials, and have provided novel approaches for manipulating thermal transport for industrial applications.
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| Research Progress Status |
令和元年度が最終年度であるため、記入しない。
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| Strategy for Future Research Activity |
令和元年度が最終年度であるため、記入しない。
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Report
(2 results)
Research Products
(6 results)
