Enhancing the Thermoelectric Performance of Mg2Sn Single Crystals via Point Defect Engineering and Sb Doping

Wataru Saito; Kei Hayashi; Zhicheng Huang; Jinfeng Dong; Jing-Feng Li; Yuzuru Miyazaki

doi:10.1021/acsami.0c17462

Enhancing the Thermoelectric Performance of Mg₂Sn Single Crystals via Point Defect Engineering and Sb Doping

ACS Appl Mater Interfaces. 2020 Dec 30;12(52):57888-57897. doi: 10.1021/acsami.0c17462. Epub 2020 Dec 15.

Authors

Wataru Saito¹, Kei Hayashi¹, Zhicheng Huang¹, Jinfeng Dong², Jing-Feng Li², Yuzuru Miyazaki¹

Affiliations

¹ Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
² State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

PMID: 33320522
DOI: 10.1021/acsami.0c17462

Abstract

Mg₂Sn is a potential thermoelectric (TE) material that exhibits environmental compatibility. In this study, we fabricated Sb-doped Mg₂Sn (Mg₂Sn_1-xSb_x) single-crystal ingots and demonstrated the enhancement of TE performance via point defect engineering and Sb doping. The Mg₂Sn_1-xSb_x single-crystal ingots exhibited considerably enhanced electrical conductivity because of the donor-doping effect in addition to high carrier mobility. Moreover, the Mg₂Sn_1-xSb_x single-crystal ingots contained Mg vacancy (V_Mg) as a point defect. The introduced V_Mg and doped Sb atoms formed nanostructures, both acting as phonon-scattering centers. Consequently, lower lattice thermal conductivity was achieved for the Mg₂Sn_1-xSb_x single-crystal ingots compared with polycrystalline counterparts. Owing to the significant enhancement in the electrical conductivity and the reduction in the lattice thermal conductivity, the maximum power factor of 5.1(4) × 10^-3 W/(K² m) and the maximum dimensionless figure of merit of 0.72(5) were achieved for the Mg₂Sn_0.99Sb_0.01 single-crystal ingot, which are higher than those of single-phase Mg₂Sn_1-xSb polycrystals.

Keywords: Mg vacancy; Mg2Sn; Sb doping; nanostructure; point defect; single crystal; thermoelectric properties.