LIU Siyi ¹, WANG Yuhang ¹, LI Hongtao ², ZHU Hongyu ¹, HUANG Wei ¹, QIN Bingke ³, SU Taichao ¹

(1. College of Science, Guilin University of Technology, Guilin 541006, Guangxi, China; 2. Shanghai Customs District of P. R.China, Shanghai 200135, China; 3. School of Chemistry and Materials Engineering, Liupanshui NormalUniversity, Liupanshui 553004, Guizhou, China)

Abstract: Quaternary compound BiCuSeO, with natural superlattice structure, has extremely low thermal conductivity and high  Seebeck  coefficient, but  its  thermoelectric properties  are restricted by  its  low  electrical  conductivity.  In this  study, BiCuSeO was prepared by using solid state reaction method and BiCuSeO/Ag composites were prepared by using pressureless sintering process with Ag₂O as precursor. The effects of Ag₂O on microstructure and thermoelectric properties of BiCuSeO were studied. It was found that Ag was mainly present in the form of metal after the pressureless sintering process, while a small fraction of Ag was incorporated into the crystal structure of BiCuSeO. While the addition of Ag varied the conduction mechanism of BiCuSeO and significantly enhanced the conductivity, it had almost no impact on the Seebeck coefficient and thermal conductivity . The figure of merit (Z) of the sample with 1 wt.% Ag₂Owas 1.5×10一4 K一 1  at room temperature, which is higher than that  of BiCuSeO by  about  20 times.  Therefore, the  incorporation  of Ag  is  an  effective  way  to  improve  the thermoelectric properties of BiCuSeO ceramics.
Key words: solid state reaction; thermoelectric ceramics; BiCuSeO; figure of merit