Microwave activated hot pressing: A new opportunity to improve the thermoelectric properties of n–type Bi2Te3 − xSex bulks

• A new consolidation method of Microwave Activated Hot Pressing was introduced.
• Bi2Te3-xSex bulks were prepared by Microwave Activated Hot Pressing.
• The doped selenium promotes grain refinement and thermoelectric properties.
• A minimum thermal conductivity of 0.85 Wm−1 K−1 was achieved for Bi2Te2.4Se0.6.

In this article, n–type Bi2Te3 − xSex (x = 0.15, 0.3, 0.45, 0.6) compounds were prepared successfully via a new consolidation technique named Microwave Activated Hot Pressing (MAHP) to explore the optimum composition with the best thermoelectric properties. The results showed that the relatively low sintering temperature and short holding time used in this work could suppress grain growth. The sintered samples showed a typical multi–scale microstructure, consisting of fine lamellar grains and irregular granular grains. Moreover, the doped selenium promoted grain refinement. With the variation of selenium content, a highest power factor of 1.75 × 10−3 Wm−1 K−2 was achieved for Bi2Te2.7Se0.3 sample around 423 K. And a minimum thermal conductivity of 0.85 Wm−1 K−1 was achieved around 423 K for Bi2Te2.4Se0.6 sample. Considering the comprehensive thermoelectric properties, a highest ZT value of 0.73 was obtained for Bi2Te2.55Se0.45 sample around 423 K.

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