Synthesis of Si based high performance thermoelectric material by fabricating all-scale phonon scattering structure

2014 Fiscal Year Final Research Report

• Project/Area Number: 25820457
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Energy engineering
• Research Institution: Osaka University
• Principal Investigator: OHISHI Yuji 大阪大学, 工学(系)研究科(研究院), 助教 (20571558)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: ナノSi / 熱電特性

Outline of Final Research Achievements

The thermoelectric properties of heavily doped n-type and p-type single crystal Si were studied. A theoretical model based on the Boltzmann transport equation was developed from the experimentally observed data. A bulk nanocrystalline Si was synthesized by ball milling and spark plasma sintering. TEM observation showed that the grain size was around 50 nm. The thermal conductivity was reduced compared to that of the single crystal Si due to the enhanced phonon scattering at grain boundaries. Further reduction of the thermal conductivity was achieved by adding NiSi2 nanoparticles and Ge impurities. However, the thermoelectric performance was not improved compared to that of Si-Ge alloys. This result suggests that optimization of the sizes of the grains and nanoparticles are necessary to reduce the thermal conductivity significantly and enhance the thermoelectric performance.

Free Research Field

材料工学