Thermoelectric properties of Bi₂Te_2.7Se_0.3 nanocomposites embedded with MgO nanoparticles

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• 作者：Sung-Jae Joo ; Ji-Hee Son ; Bok-Ki Min ; Ji-Eun Lee…
• 关键词：Bi2Te2.7Se0.3 ; MgO ; Nanoparticle ; Thermoelectric ; Nanocomposite
• 刊名：Journal of the Korean Physical Society
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：69
• 期：8
• 页码：1314-1320
• 全文大小：995 KB
• 刊物主题：Physics, general; Theoretical, Mathematical and Computational Physics; Particle and Nuclear Physics;
• 出版者：Springer Netherlands
• ISSN：1976-8524
• 卷排序：69

文摘

Bi₂Te_2.7Se_0.3 bulk materials containing x vol% MgO nanoparticles (average particle size ≈ 100 nm, x = 0, 0.5, 1.0, 1.5) were synthesized by using high-energy ball milling and plasma- activated sintering (PAS) without any special process for nanoparticle dispersion. A microstructure investigation using a scanning electron microscope (SEM) confirmed that MgO nanoparticles were properly dispersed in the Bi₂Te_2.7Se_0.3 matrix and that the grain size was smaller in MgO-containing samples due to suppressed grain growth. The resistivity and the maximum Seebeck coefficient of Bi₂Te_2.7Se_0.3 increased with increasing MgO content whereas the thermal conductivity decreased in the measurement temperature range of 298 K - 573 K. As a result, the maximum dimensionless figure of merit, ZT_max, increased about 8.5% in this study, from 0.806 for pristine Bi₂Te_2.7Se_0.3 to 0.875 when x = 1.5. The ZT_max was observed to shift to lower temperature, the electron concentration to decrease, and the electron mobility to increase with increasing x, which were explained using a hypothesis that the Te_Bi antisite defect concentration decreased as the MgO content increased. In summary, the addition of MgO nanoparticles has been shown to be a simple and effective method to improve the low-temperature thermoelectric properties of n-type Bi₂Te₃ materials.