Enhanced Thermoelectric Performance of Mg-Doped AgSbTe2 by Inhibiting the Formation of Ag2Te

Rui Du; Guangbiao Zhang; Min Hao; Xiaowei Xuan; Panpan Peng; Pengya Fan; Haotian Si; Gui Yang; Chao Wang

doi:10.1021/acsami.2c22930

Enhanced Thermoelectric Performance of Mg-Doped AgSbTe₂ by Inhibiting the Formation of Ag₂Te

ACS Appl Mater Interfaces. 2023 Feb 7. doi: 10.1021/acsami.2c22930. Online ahead of print.

Authors

Rui Du^{1

2}, Guangbiao Zhang^{1

2}, Min Hao^{1

2}, Xiaowei Xuan^{1

2}, Panpan Peng^{1

2}, Pengya Fan^{1

2}, Haotian Si^{1

2}, Gui Yang³, Chao Wang^{1

2}

Affiliations

¹ Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, China.
² International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China.
³ School of Mechanical and Electrical Engineering, Chuzhou University, Chuzhou 239000, China.

PMID: 36749154
DOI: 10.1021/acsami.2c22930

Abstract

The existence of Ag₂Te has always been an obstacle for p-type thermoelectric material AgSbTe₂ to improve its thermoelectric performance. In this work, AgSb_1-xMg_xTe₂ samples are synthesized by melting-slow-cooling and then spark plasma sintering (SPS). Through increasing the solubility of Ag₂Te in the AgSbTe₂ matrix by Mg doping, the formation of Ag₂Te is inhibited. Density functional theory calculations confirm more valence bands are involved in electrical transport due to Mg doping. Therefore, the electrical conductivity of AgSb_1-xMg_xTe₂ samples has been greatly improved due to the reduction of Ag₂Te with n-type electrical conductivity. Moreover, the downward trend of ZT, which is caused by the structural transition of Ag₂Te at about 418 K, disappears. Meanwhile, lattice defects form in the AgSb_0.98Mg_0.02Te₂ sample, and Mg doping improves the configurational entropy change, resulting in a decrease in lattice thermal conductivity over the entire temperature range of measurement. Finally, a high ZT value of 1.31 at 523 K is achieved for the AgSb_0.98Mg_0.02Te₂ sample. This study demonstrates that Mg doping can effectively improve AgSbTe₂ thermoelectric performance by inhibiting the formation of the Ag₂Te impurity phase.

Keywords: Ag2Te secondary phase; AgSbTe2; Mg doping; microstructure; thermoelectric properties.