Rational deign, two-step synthesis of Cu2GeS3 crystal with enhanced thermoelectric performance by Te alloying

作者：Hu, Zeqing; Xu, Huihong; Lin, Yangjian; Liu, Yu; Xu, Junsheng; Li, Zhou^*; Song, Jiming^*

来源：Journal of Materials Science: Materials in Electronics , 2022, 33(19): 15894-15903.

DOI：10.1007/s10854-022-08488-z

• CU2SNSE3
• TRANSFORMATION
• GROWTH

Currently, Cu2GeS3 has been obtained through solid-state reaction. However, the pure phase Cu2GeS3 synthesized still faces challenges due to the low boiling point of the sulfur element. Herein, we have prepared pristine Cu2GeS3 by a two-step method. Firstly, the pure phase GeS2 was synthesized by solvothermal method and then used the freshly as-synthesized GeS2 as raw material to react with copper powder to fabricate pure phase Cu2GeS3. Further, the thermoelectric properties of Cu2GeS3 crystal have been explored. At room temperature, the electric resistance value measured by multimeter was similar to 2634 Omega for intrinsic Cu2GeS3 crystal, which exceeded the instrument (electrical conductivity/Seebeck coefficient) test range of 0-2000 Omega, so there is no relevant report in the thermoelectric field about Cu2GeS3 crystal. In order to improve its conductivity, Cu2GeS3 crystal is alloyed with a small amount of Te powder to obtainable Cu2GeS3-xTex samples, which have obvious thermoelectric properties. By adjusting the content of Te, finally, the electrical conductivity of the Cu3GeS2.6Te0.4 sample reached 364.20 S m(-1) and the figure-of-merit ZT(max) value of similar to 0.12 were obtained at 816 K.