Thermoelectric properties of Ag1−xGaTe2 with chalcopyrite structure

Abstract

In the present study, we investigated the high-temperature thermoelectric (TE) properties of AgGaTe2 with chalcopyrite structure. We tried to enhance the TE properties of AgGaTe2 by reducing the Ag content. The reduction of Ag increased the carrier concentration, leading to enhancement of the dimensionless figure of merit (ZT). The maximum ZT value was 0.77 at 850 K obtained in Ag0.95GaTe2, which was approximately two times higher than that of stoichiometric AgGaTe2.

High thermoelectric performance of oxyselenides: intrinsically low thermal conductivity of Ca-doped BiCuSeO

“…The figure of merit, ZT, increased significantly from 0.53 for pure BiCuSeO to 0.9 for Bi 0.925 Ca 0.075 CuSeO at 923 K, which is higher than that of most thermoelectric materials with intrinsically low thermal conductivity reported thus far. [13][14][15][16][17][18][19][20] These results suggest that the BiCuSeO system is a robust candidate for medium-temperature thermoelectric applications. Further improvement in the ZT may be achieved by increasing the electrical conductivity via heavy hole doping either using conductive (Cu 2 Se 2 ) 2 À layers or insulating (Bi 2 O 2 ) 2 þ layers and/or by improving the carrier mobility.…”

“…22 The ZT value of Bi 0.925 Ca 0.075 CuSeO at 873 K is also higher than that of 0.7 for Bi 0.90 Sr 0.10 CuSeO at 873 K. 21 The present ZT of 0.9 is higher than most thermoelectric materials with intrinsically low thermal conductivity reported so far. [13][14][15][16][17][18][19][20] Therefore, it can be concluded that the higher thermoelectric performance of BiCuSeO is mainly due to the intrinsically low thermal conductivity of the material.…”

“…Alternatively, high-performance single-phase thermoelectric materials can be obtained using materials with intrinsically low lattice thermal conductivities. Typical materials included in this class are as follows: AgSbTe 2 (kB0.39 Wm À1 K À1 , ZTB1.6 at 673 K), 10,11 Ag 9 TlTe 5 (kB0.22 Wm À1 K À1 , ZTB1.2 at 700 K), 12 Ag 0.95 GaTe 2 (kB0.20 Wm À1 K À1 , ZTB0.7 at 850 K), 13 Ag 3.9 Mo 9 Se 11 (kB0.75 Wm À1 K À1 , ZTB0.6 at 800 K), 14 Cu 3 SbSe 4 (kB0.50 Wm À1 K À1 , ZTB0.8 at 650 K), 15 Cu 2 Ga 4 Te 7 (kB0.67 Wm À1 K À1 , ZTB0.6 at 940 K), 16 Cu 2.1 Zn 0.9 SnSe 4 (kB0.50 Wm À1 K À1 , ZTB0.9 at 860 K), 17 Cu 2 Ga 0.07 Ge 0.93 Se 3 (kB0.67 Wm À1 K À1 , ZTB0.5 at 745 K), 18 CsBi 4 Te 6 (kB0.50 Wm À1 K À1 , ZTB0.8 at 275 K), 19 and K 2 Bi 8 Se 13 (kB0.80 Wm À1 K À1 , ZTB0.4 at 400 K). 20 Recently, we reported a quaternary BiCuSeO compound that exhibits very low thermal conductivity.…”

Solid Solution Series between CdIn2Te4 and AgInTe2 Investigated by Resonant X‐ray Scattering

“…580°C. [2,3] AgInTe 2 , on the other hand, reaches a ZT value of only 0.06 due to its low electrical conductivity, though the corresponding electrical bandgap of 1 eV is promising for the application as a solar cell material. [4] It crystallizes in the chalcopyrite structure type (space group I42d; CuFeS 2 -type) as derived from synchrotron powder diffraction data.…”

Tuning the carrier concentration to improve the thermoelectric performance of CuInTe2 compound

“…9 In order to further improve the TE performance, we need to explore new materials such as chalcopyrites CuGaTe 2 , 10,11 and AgGaTe 2 . 12,13 This kind of compounds were found to exhibit larger ZT value at high temperature region, which can be explained by significant decrease in the thermal conductivity at increased temperature.…”