RESUMO
Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco-friendly constituting elements. Here, adopting a unique synthesis route via chemical co-precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics ( P F max = $PF_{\text{max}} =$ 21.5 µW cm-1 K-2 and z T max = $zT_{\text{max}} =$ 0.5 at 1100 K in Zn 0.96 Al 0.04 O ${\rm Zn}_{0.96} {\rm Al}_{0.04}{\rm O}$ ) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi-dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics.
RESUMO
In this work, Bi1-xPbxCu1-x SeO (x = 0, 0.02, 0.06, and 0.08) compounds were synthesized by a solid state reaction followed by spark plasma sintering. The effect of simultaneous Bi to Pb substitution and Cu vacancy introduction on thermoelectric properties was investigated systematically. The power factor was significantly enhanced, contributing to the increase in the zT value. As a result, the zTmax of 0.75 at 773 K was obtained for the Bi0.94Pb0.06Cu0.94SeO sample. To reveal the factors constraining the zTmax of Bi1-xPbxCuSeO-based oxyselenides, a further careful analysis of literature data was performed. We highlighted that for Pb-doped oxyselenides, the power factor is almost independent of the synthesis technique, while the lattice thermal conductivity is the main property determining zTmax and is highly affected by the synthesis method.
