| Abstract |
| Thermoelectric energy conversion has attracted much attention as an efficient and environment-friendly energy technology. Thermoelectric energy conversion performance is directly influenced by the figure of merit (ZT) of the thermoelectric material, however, most known thermoelectric materials with high ZT contain toxic and/or scarce elements. Herein, we report the thermoelectric properties of a polycrystalline p-type Si composite. Si is not only one of the most abundant elements in the earth’s crust and but also non-toxic. The composite was prepared by consolidating melt-spun B-doped Si ribbons using spark plasma sintering to achieve a nanocrystalline composite. However, unexpectedly, the resulting material was composed of micron-sized grains with submicron-sized pores. This microstructural character provided unexpected benefits from a thermoelectric point of view. First, the mobility of the composite was quite compatible with that of single crystalline B-doped Si wafer, as elucidated by our calculations based on Masseti's formula. Furthermore, the hole concentration was increased in the compound compared to the B-doped Si wafer, due to unintentional Cu-doping during the melt-spinning process, which resulted in enhanced electrical conductivity. Notably, the lattice thermal conductivity was significantly reduced by the existence of pores, while the electrical conductivity was enhanced. This phonon-glass electron-crystal (PGEC), realized in the polycrystalline p-type Si composite, could lead to an increase in ZT. (Received June 8, 2018; Accepted July 4, 2018) |
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| Key Words |
| thermoelectric, Si, melt-spinning, spark plasma sintering |
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