Ultra-fast synthesis and high thermoelectric properties of heavy sodium doped BiCuSeO

BiCuSeO is a promising material for application in thermoelectric energy conversion with intrinsic low thermal conductivity. However, it is challenging to synthesize the efficient high-quality BiCuSeO on a large scale for further practical applications. In this work, BiCuSeO samples have been successfully fabricated in less than 20 min though self-propagating high-temperature synthesis (SHS) combined with spark plasma sintering (SPS) method. In addition, it is found that the thermoelectric performance can be greatly improved by heavy sodium doping. The electrical conductivity can be improved from 1.6 to 200 S cm(-1) at 323 K while the Seebeck coefficient is moderated decreased with sodium doping content, leading to a maximum power factor of 467 mW cm(-1) K-2. Furthermore, the lattice thermal conductivity and total thermal conductivity significantly decrease with sodium doping due to strongly phonon scattering by the point defects. The combination of optimized power factor and lower thermal conductivity resulted to a higher ZT value of 0.70 at 873 K for Bi0.85Na0.15CuSeO, which is about 100% higher than that of the pristine BiCuSeO. Our work opens a new path for ultra-fast, low cost, mass production fabrication of oxychalcogenides -based materials. (C) 2017 Elsevier B.V. All rights reserved.