Scrap Recovery of n-Type Bismuth Telluride Ingot by Second Zone Melting and PbBr₂ Doping

Bismuth telluride is the only commercially applied thermoelectric material. The n-type material is usually prepared by the method of zone melting; however, the utilization ratio of the ingot is relatively low, owing to the bad thermoelectric performance of the two ends. Herein, the waste of n-type bismuth telluride is recovered by the second zone melting and PbBr2 doping. It is shown that the second zone melting can improve the grain alignment, leading to the increase of carrier mobility. When PbBr2 doping is introduced, lattice thermal conductivity is largely reduced by the high dense dislocations. As a result, the peak power factor and maximum ZT reach 53 & mu;W cm(-1) K-2 and 1.15, respectively, which are even higher than the values of the original commercial material. This work provides an economic and applicable strategy to recover the waste of bismuth telluride thermoelectric materials.