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<p>This study investigates the synergistic effects of Ag and Mn co-doping on the thermoelectric performance and band gap evolution of p-type Bi<sub>0.5</sub>Sb<sub>1.5</sub>Te<sub>3</sub> alloys fabricated via scalable melting and hot-pressing. Using Bi<sub>0.5</sub>Sb<sub>1.5</sub>Te<sub>3</sub> + 0.075 wt% Ag as a reference, Bi<sub>0.5</sub>Sb<sub>1.5-y</sub>Mn<sub>y</sub>Te<sub>3</sub> + 0.075 wt% Ag (<i>y</i> = 0, 0.0025, 0.0075, 0.015) samples were synthesized. For practical scalability, 200&#xa0;g batch ingots were sintered into 50&#xa0;mm disks. Ag and Mn acted as acceptors, increasing carrier concentration. While this resulted in a slight reduction in the power factor, the expansion of the band gap effectively suppressed the bipolar effect at elevated temperatures. Co-doping of Ag and Mn shifted the Seebeck coefficient peak and reduced lattice thermal conductivity. Notably, the lattice thermal conductivity was suppressed above 423&#xa0;K, showing a 20–23% reduction at 573&#xa0;K. Consequently, the optimized composition Bi<sub>0.5</sub>Sb<sub>1.4925</sub>Mn<sub>0.0075</sub>Te<sub>3</sub> + 0.075 wt% Ag achieved a maximum <i>ZT</i> (<i>ZT</i><sub>max</sub>) of 0.97 at 473&#xa0;K. While this value is comparable to the <i>ZT</i><sub>max</sub> of the Ag single-doped sample (<i>y</i> = 0), the peak temperature shifted from 423 to 473&#xa0;K, improving high-temperature thermoelectric performance. Furthermore, the average <i>ZT</i> (<i>ZT</i><sub>avg</sub>) in the 473–573&#xa0;K range, a common range for industrial waste heat recovery, was 0.85, marking a 10.4% improvement compared to Ag single-doping. These findings propose Ag/Mn co-doping as a promising strategy to extend the operating range of Bi-Te-based materials for mid-temperature applications.</p> Graphical Abstract <p></p>

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Synergistic Effect of Ag/Mn Co-doping on the High-Temperature Thermoelectric Properties of Bi0.5Sb1.5Te3

  • 期刊论文

  • 发表日期：

    2026年7月18日

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  • Ye-Ji Shin,
  • Eun-Ji Meang,
  • Joseph Ngugi Kahiu,
  • Hyoju Son,
  • Kwan-Ho Park,
  • Jaehan Chung,
  • Ho Seong Lee

摘要

This study investigates the synergistic effects of Ag and Mn co-doping on the thermoelectric performance and band gap evolution of p-type Bi0.5Sb1.5Te3 alloys fabricated via scalable melting and hot-pressing. Using Bi0.5Sb1.5Te3 + 0.075 wt% Ag as a reference, Bi0.5Sb1.5-yMnyTe3 + 0.075 wt% Ag (y = 0, 0.0025, 0.0075, 0.015) samples were synthesized. For practical scalability, 200 g batch ingots were sintered into 50 mm disks. Ag and Mn acted as acceptors, increasing carrier concentration. While this resulted in a slight reduction in the power factor, the expansion of the band gap effectively suppressed the bipolar effect at elevated temperatures. Co-doping of Ag and Mn shifted the Seebeck coefficient peak and reduced lattice thermal conductivity. Notably, the lattice thermal conductivity was suppressed above 423 K, showing a 20–23% reduction at 573 K. Consequently, the optimized composition Bi0.5Sb1.4925Mn0.0075Te3 + 0.075 wt% Ag achieved a maximum ZT (ZTmax) of 0.97 at 473 K. While this value is comparable to the ZTmax of the Ag single-doped sample (y = 0), the peak temperature shifted from 423 to 473 K, improving high-temperature thermoelectric performance. Furthermore, the average ZT (ZTavg) in the 473–573 K range, a common range for industrial waste heat recovery, was 0.85, marking a 10.4% improvement compared to Ag single-doping. These findings propose Ag/Mn co-doping as a promising strategy to extend the operating range of Bi-Te-based materials for mid-temperature applications.

Graphical Abstract