Enhanced thermoelectric performance in n-type Mg3.2Sb1.5Bi0.5 doping with lanthanides at the Mg site. (10th November 2022)

• Record Type: Journal Article
• Authors: Yu, Lu; Zhang, Zipei; Li, Juan; Li, Wenhao; Wei, Shikai; Wei, Sitong; Lu, Guiwu; Song, Weiyu; Zheng, Shuqi
• Is Part Of: Journal of materials science & technology. Volume 127(2022)
• Page Start: 108
• Page End: 114
• Publication Date: 2022-11-10
• Subjects: Thermoelectric material -- First-principles calculation -- Mg3.2Sb1.5Bi0.5; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2022.02.054
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: Gd and Ho have increased the DOS of the valence band near the Fermi level, and the d electrons of Gd and Ho have made extraordinary contributions. Gd and Ho are effective n-type cation site dopants with higher doping efficiency and better carrier concentration than the anion site dopants chalcogenide elements. For Mg3.2 Gd0.02 Sb1.5 Bi0.5 and Mg3.2 Ho0.02 Sb1.5 Bi0.5 samples, we obtain high zT values of 1.61 and 1.55 at 725 K, respectively. Gd as well as Ho are an alternative effective n-type doping element for higher thermoelectric performance. Abstract: Mg-based thermoelectric materials have attracted more and more attention because of their rich composition elements, green environmental protection, and lower price. In recent years, the thermoelectric properties of n-type Mg3 Sb2 materials have been optimized by doping chalcogenide elements (S, Se, and Te) at the anionic position. In this work, n-type Mg3.2 Ax Sb1.5 Bi0.5 ( A = Gd, Ho; x = 0.01, 0.02, 0.03, and 0.4) samples were prepared by the cation site doping of lanthanide elements (Gd and Ho). The research results show that Gd and Ho doped n-type Mg3.2 Sb1.5 Bi0.5 samples are entirely comparable to the S, Se, and Te doped n-type Mg3.2 Sb1.5 Bi0.5 samples, demonstrating more excellent thermoelectric properties. Doping with lanthanides (Gd and Ho) at the Mg site increases the carrier concentration of the material to 8.161 × 10 19 cm −3 . Doping induces the contribution of more electron, thus obtaining higher conductivity. The maximum zT value of the Mg3.2 Gd0.02 Sb1.5 Bi0.5 and the Mg3.2 Ho0.02 Sb1.5 Bi0.5 samples reaches 1.61 and 1.55, respectively. This work theoretically and experimentally demonstrates Gd and Ho are efficient n-type dopants for Mg3.2 Sb1.5 Bi0.5 thermoelectric material.