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High-Performance Low-Cost n-Type Se-Doped Mg3Sb2-Based Zintl Compounds for Thermoelectric Application

Zhang, Jiawei; Song, Lirong; Mamakhel, Aref; Jørgensen, Mads Ry Vogel LU and Iversen, Bo Brummerstedt (2017) In Chemistry of Materials 29(12). p.5371-5383
Abstract

Thermoelectric materials, capable of converting heat directly into electricity without moving parts, provide a promising solid-state solution for waste heat harvesting. However, currently available commercial thermoelectric materials PbTe and Bi2Te3 are based on tellurium, an extremely scarce and expensive element, which prohibits large scale applications. Herein, we present a systematic study on a new low-cost Te-free material, n-type Se-doped Mg3Sb1.5Bi0.5, by combining the structure and property characterization with electronic structure and electrical transport modeling. Compared with pure Mg3Sb2, Se-doped Mg3Sb1.5Bi0.5... (More)

Thermoelectric materials, capable of converting heat directly into electricity without moving parts, provide a promising solid-state solution for waste heat harvesting. However, currently available commercial thermoelectric materials PbTe and Bi2Te3 are based on tellurium, an extremely scarce and expensive element, which prohibits large scale applications. Herein, we present a systematic study on a new low-cost Te-free material, n-type Se-doped Mg3Sb1.5Bi0.5, by combining the structure and property characterization with electronic structure and electrical transport modeling. Compared with pure Mg3Sb2, Se-doped Mg3Sb1.5Bi0.5 shows the considerably enhanced power factor as well as much lower thermal conductivity. The excellent electrical transport originates from a nontrivial near-edge conduction band with six conducting carrier pockets and a light conductivity effective mass as well as the weak contribution from a secondary conduction band with a valley degeneracy of 2. The accurate location of the conduction band minimum is revealed from the Fermi surface, which appears to be crucial for the understanding of the electronic transport properties. In addition, the total thermal conductivity is found to be reasonably low (∼0.62 W m-1 K-1 at 725 K). As a result, an optimal zT of 1.23 at 725 K is obtained in Mg3.07Sb1.5Bi0.48Se0.02. The high zT, as well as the earth-abundant constituent elements, makes the low-cost Se-doped Mg3Sb1.5Bi0.5 a promising candidate for the intermediate-temperature thermoelectric application. Moreover, the systematic electronic structure and transport modeling provide an insightful guidance for the further optimization of this material and other related Zintl compounds.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Chemistry of Materials
volume
29
issue
12
pages
13 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85021404826
ISSN
0897-4756
DOI
10.1021/acs.chemmater.7b01746
language
English
LU publication?
yes
id
3016800d-feb7-4d3b-a72b-d2912688b710
date added to LUP
2017-07-11 12:22:14
date last changed
2018-01-07 12:11:16
@article{3016800d-feb7-4d3b-a72b-d2912688b710,
  abstract     = {<p>Thermoelectric materials, capable of converting heat directly into electricity without moving parts, provide a promising solid-state solution for waste heat harvesting. However, currently available commercial thermoelectric materials PbTe and Bi<sub>2</sub>Te<sub>3</sub> are based on tellurium, an extremely scarce and expensive element, which prohibits large scale applications. Herein, we present a systematic study on a new low-cost Te-free material, n-type Se-doped Mg<sub>3</sub>Sb<sub>1.5</sub>Bi<sub>0.5</sub>, by combining the structure and property characterization with electronic structure and electrical transport modeling. Compared with pure Mg<sub>3</sub>Sb<sub>2</sub>, Se-doped Mg<sub>3</sub>Sb<sub>1.5</sub>Bi<sub>0.5</sub> shows the considerably enhanced power factor as well as much lower thermal conductivity. The excellent electrical transport originates from a nontrivial near-edge conduction band with six conducting carrier pockets and a light conductivity effective mass as well as the weak contribution from a secondary conduction band with a valley degeneracy of 2. The accurate location of the conduction band minimum is revealed from the Fermi surface, which appears to be crucial for the understanding of the electronic transport properties. In addition, the total thermal conductivity is found to be reasonably low (∼0.62 W m<sup>-1</sup> K<sup>-1</sup> at 725 K). As a result, an optimal zT of 1.23 at 725 K is obtained in Mg<sub>3.07</sub>Sb<sub>1.5</sub>Bi<sub>0.48</sub>Se<sub>0.02</sub>. The high zT, as well as the earth-abundant constituent elements, makes the low-cost Se-doped Mg<sub>3</sub>Sb<sub>1.5</sub>Bi<sub>0.5</sub> a promising candidate for the intermediate-temperature thermoelectric application. Moreover, the systematic electronic structure and transport modeling provide an insightful guidance for the further optimization of this material and other related Zintl compounds.</p>},
  author       = {Zhang, Jiawei and Song, Lirong and Mamakhel, Aref and Jørgensen, Mads Ry Vogel and Iversen, Bo Brummerstedt},
  issn         = {0897-4756},
  language     = {eng},
  month        = {06},
  number       = {12},
  pages        = {5371--5383},
  publisher    = {The American Chemical Society},
  series       = {Chemistry of Materials},
  title        = {High-Performance Low-Cost n-Type Se-Doped Mg<sub>3</sub>Sb<sub>2</sub>-Based Zintl Compounds for Thermoelectric Application},
  url          = {http://dx.doi.org/10.1021/acs.chemmater.7b01746},
  volume       = {29},
  year         = {2017},
}