Enhanced Thermoelectric Properties of Solution Grown Bi2Te3鈥?i>xSex Nanoplatelet Composites

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• 作者：Ajay Soni ; Zhao Yanyuan ; Yu Ligen ; Michael Khor Khiam Aik ; Mildred S. Dresselhaus ; Qihua Xiong
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：March 14, 2012
• 年：2012
• 卷：12
• 期：3
• 页码：1203-1209
• 全文大小：439K
• 年卷期：v.12,no.3(March 14, 2012)
• ISSN：1530-6992

文摘

We report on the enhanced thermoelectric properties of selenium (Se) doped bismuth telluride (Bi₂Te_3鈥?i>xSe_x) nanoplatelet (NP) composites synthesized by the polyol method. Variation of the Se composition within NPs is demonstrated by X-ray diffraction and Raman spectroscopy. While the calculated lattice parameters closely follow the Vegard鈥檚 law, a discontinuity in the shifting of the high frequency (E_g² and A_1g²) phonon modes illustrates a two mode behavior for Bi₂Te_3鈥?i>xSe_x NPs. The electrical resistivity (蟻) of spark plasma sintered pellet composites shows metallic conduction for pure Bi₂Te₃ NP composites and semiconducting behavior for intermediate Se compositions. The thermal conductivity (魏) for all NP composites is much smaller than the bulk values and is dominated by microstructural grain boundary scattering. With temperature dependent electrical and thermal transport measurements, we show that both the thermoelectric power S (鈭?59 渭V/K) and the figure of merit ZT (0.54) are enhanced by nearly a factor of 4 for SPS pellets of Bi₂Te_2.7Se_0.3 in comparison to Bi₂Te₃ NP composites. Tentatively, such an enhancement of the thermoelectric performance in nanoplatelet composites is attributed to the energy filtering of low energy electrons by abundant grain boundaries in aligned nanocomposites.

Keywords:

Thermoelectric figure of merit; nanocomposites; Bi₂Te_3鈭?i>xSe_x nanoplatelets; energy filtering; polyol synthesis