Enhanced Thermoelectric Properties of n‐type Mg₃Sb₂ by Excess Magnesium and Tellurium Doping

Abstract

Mg 3 Sb 2 shows poor comprehensive thermoelectric properties mainly because its conductivity is very poor, despite it has very low thermal conductivity. Excess Mg combined with small amount of Te doping can control carrier type and carrier concentration. The semiconductor and metallic transport mechanism coordinate to control the electrical transport characteristics and improve the electrical transport performance. The lattice thermal conductivity of Mg 3 Sb 2 decreases after Te doping. The maximum ZT value is 0.78 for Mg 3.2 Sb 1.99 Te 0.01 at 773 K.

Rapid One‐Step Synthesis and Compaction of High‐Performance n‐Type Mg3Sb2 Thermoelectrics

“…The superior power factor in combination with the low thermal conductivity results in excellent overall TE performance in n‐type (Sc, Te)‐doped Mg 3 Sb 2 . In Te‐doped samples, n‐type Mg 3.5 Sb 1.97 Te 0.03 shows an optimal zT ranging from 0.21 at 300 K to 0.96 at 725 K (Figure b; Supporting Information, Figure S11 a), which is slightly higher than those reported in n‐doped Mg 3 Sb 2 without the Mg 3 Bi 2 alloying . Among Sc‐doped samples, an optimal zT of 0.21–1.13 at 300–725 K is realized in the n‐type Mg 3.5 Sc 0.05 Sb 2 sample (Figure b; Supporting Information, Figure S11 b).…”

“…An optimal zT value as high as about 1.5 at 725 K is obtained in (Sc, Te)‐co‐doped Mg 3 Sb 2 samples prepared by the one‐step SPS (Figure b), outperforming any reported n‐type Mg 3 Sb 2 samples without the Mg 3 Bi 2 alloying. High zT values of 0.4–1.5 over a wide range of temperatures from 300 to 725 K in (Sc, Te)‐co‐doped Mg 3 Sb 2 give rise to a high average zT of about 0.9 (see Figure c), approximately two times higher than those of the previously reported Te‐doped Mg 3 Sb 2 . The high zT value is typically contributed by the enhanced power factor and reduced thermal conductivity induced by the Sc and Te co‐doping.…”

“…Q represents the n‐type dopant. Temperature‐dependent b) zT and c) average zT within the temperature range of 300–725 K for n‐type Mg 3+ δ Sc y Sb 2− x Te x ( δ =0.5) prepared by the one‐step SPS in comparison with those of the reported n‐type Mg 3 Sb 2 samples without alloying with Mg 3 Bi 2 .…”

“…In Te-doped samples, n-type Mg 3.5 Sb 1.97 Te 0.03 shows an optimal zT ranging from 0.21 at 300 K to 0.96 at 725 K (Figure 1 b; Supporting Information, Figure S11 a), which is slightly higher than those reported in n-doped Mg 3 Sb 2 without the Mg 3 Bi 2 alloying. [13,[27][28][29] Among Sc-doped samples, an optimal zT of 0.21-1.13 at 300-725 K is realized in the n-type Mg 3.5 Sc 0.05 Sb 2 sample (Figure 1 b; Supporting Information, Figure S11 b). By co-doping with Sc and Te, zT values can be further enhanced to 0.4-1.5 at 300-725 K in the n-type Mg 3.5 Sc 0.04 Sb 1.97 Te 0.03 (Figure 1 b; Supporting Information, Figure S11 c).…”

“…High zT values of 0.4-1.5 over a wide range of temperatures from 300 to 725 K in (Sc, Te)-co-doped Mg 3 Sb 2 give rise to a high average zT of about 0.9 (see Figure 1 c), approximately two times higher than those of the previously reported Te-doped Mg 3 Sb 2 . [13,[27][28][29] The high zT value is typically contributed by the enhanced power factor and reduced thermal conductivity induced by the Sc and Te co-doping.…”