Enhanced thermoelectric properties of Mg2Si0.3Sn0.7 via Bi-doping under high pressure

• Published in: Journal of alloys and compounds 2024-06, Vol.987, p.174215, Article 174215
• Main Authors: Zhao, Haidong, Wang, Dan, Wang, Binhao, Song, Aihua, Chen, Chen, Hu, Wentao, Yu, Dongli, Xu, Bo, Tian, Yongjun
• Format: Article
• Language: English
• Subjects: Band convergence; High pressure synthesis; Mg2Si; Thermoelectric performance
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2024.174215

A series of n-type Mg2(Si0.3Sn0.7)1-xBix compounds with 0≤x≤0.02 were successfully synthesized through a combined approach involving solid-state reaction, high-pressure synthesis, and spark plasma sintering techniques. The method yielded homogeneously distributed single-phase materials at the micron scale, although minor compositional variations were detected within nanoscale precipitates embedded in the grains. The sample with Bi content of 0.01 exhibited enhanced thermoelectric properties, reaching a peak thermoelectric figure of merit (ZT) of 1.45 at 700 K while maintaining an average ZT of about 1.1 over the temperature range of 300−773 K. The enhancement in thermoelectric performance is ascribed to the optimized carrier concentration, band convergence, and refined microstructure. The findings suggest a simplified approach to doping that could be beneficial in creating high-performance thermoelectric materials for energy conversion. •Successfully fabricated Mg2(Si0.3Sn0.7)1-xBix bulks via solid-state reaction, high-pressure and spark plasma sintering.•The samples are homogeneous at the micrometer scale and slight compositional fluctuations at nanoscale.•The ZTmax of 1.45 at 700 K and ZTave of about 1.1 (300‐773 K) was achieved in optimal Mg2(Si0.3Sn0.7)0.99Bi0.01.•The high-pressure synthesis process is an effective strategy for doping.