Synergistically optimized electron and phonon transport of p-type BiCuSeO oxyselenides via Pb dopant and Te composite

Abstract

Layer-structured BiCuSeO oxyselenides with intrinsic low lattice thermal conductivity, non-toxicity, non-pollution and outstanding thermal stability is regarded as a promising thermoelectric material, but its application is limited by the poor electrical conductivity. In this paper, Pb-doped BiCuSeO (Bi1-xPbxCuSeO) was fabricated via a fast preparation method combined self-propagating high-temperature synthesis (SHS) with spark plasma sintering (SPS). Although Pb doping could greatly improve the electrical conductivity of BiCuSeO, the thermal conductivity increased as well, and it limits the thermoelectric performance. To further optimize the electron and phonon transport properties, Te powders and Te nanowires were introduced in Bi0·9Pb0·1CuSeO by ball milling, respectively. As a result, the thermal conductivity largely decreased with a maintained electrical performance. Ultimately, a maximum ZT value of 1.0 at 873 K was achieved for the 5 vol% Te nanowire + Bi0·9Pb0·1CuSeO sample, which is about 2.5 times as large as that for pristine BiCuSeO. Our work paves an alternative strategy for tuning the thermoelectric performance of BiCuSeO through Bi site doping combined low-dimension nanocomposites.