Enhancement of average thermoelectric figure of merit by increasing the grain-size of Mg3.2Sb1.5Bi0.49Te0.01

Tsutomu Kanno, Hiromasa Tamaki, Hiroki K. Sato, Stephen Dongmin Kang, Saneyuki Ohno, Kazuki Imasato, Jimmy Jiahong Kuo, G. Jeffrey Snyder, Yuzuru Miyazaki

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Abstract

Zintl compound n-type Mg3(Sb,Bi)2 was recently found to exhibit excellent thermoelectric figure of merit zT (∼1.5 at around 700 K). To improve the thermoelectric performance in the whole temperature range of operation from room temperature to 720 K, we investigated how the grain size of sintered samples influences electronic and thermal transport. By increasing the average grain size from 1.0 μm to 7.8 μm, the Hall mobility below 500 K was significantly improved, possibly due to suppression of grain boundary scattering. We also confirmed that the thermal conductivity did not change by increasing the grain size. Consequently, the sample with larger grains exhibited enhanced average zT. The calculated efficiency of thermoelectric power generation reaches 14.5% (ΔT = 420 K), which is quite high for a polycrystalline pristine material.

Original languageEnglish
Article number033903
JournalApplied Physics Letters
Volume112
Issue number3
DOIs
Publication statusPublished - 2018 Jan 15

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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    Kanno, T., Tamaki, H., Sato, H. K., Kang, S. D., Ohno, S., Imasato, K., Kuo, J. J., Snyder, G. J., & Miyazaki, Y. (2018). Enhancement of average thermoelectric figure of merit by increasing the grain-size of Mg3.2Sb1.5Bi0.49Te0.01. Applied Physics Letters, 112(3), [033903]. https://doi.org/10.1063/1.5016488