Abstract
The Bi2Te3-based thermoelectric crystal ingots produced by the zone-melting (ZM) are the most widely used commercially at present. However, the poor mechanical properties caused by the ZM are unfavorable to the production of miniature devices. The mechanical properties can be improved by the powder metallurgy (PM), but the PM results in performance degradation of n-type Bi2Te3-based alloys, which could be attributed to the disappearance of intrinsic anisotropy and the increased carrier concentration originated from the “donor-like” effect of grain boundary. In this paper, the Bi2Te2.7Se0.3 + 4 wt% Te (BTST) powder was from the ground ZM ingots, and the influence of CuO doping on the thermoelectric properties of hot-pressed BTST polycrystalline bulks with a large size was investigated. It can be found that the thermoelectric properties of BTST are improved remarkably by CuO doping due to the increased Seebeck coefficient and suppressed thermal conductivity, which is caused by the synthetic effects of optimised carrier concentration, increased effective mass, and enhanced phonon scattering by the Cu2Te/Bi2Te2.7Se0.3 hetero-interfaces. Finally, the dimensionless thermoelectric figure of merit (ZT) of the sample (CuO)0.1(Bi2Te2.7Se0.3 + 4 wt% Te) reaches 1.32 at 408 K, which is about 65 % higher than that of the pristine BTST, and its average ZTave value reaches 1.27 in the temperature range of 300–473 K. The large size bulks produced by this method are not only commercialized directly, but also avoid the problem of poor mechanical properties.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call