Strained Endotaxial PbS Nanoprecipitates Boosting Ultrahigh Thermoelectric Quality Factor in n ‐Type PbTe As‐Cast Ingots

An ideal thermoelectric material requests a weak coupling between charge and phonon transport, i.e., a high thermoelectric quality factorµ/ κL. In this work an interesting periodically strained PbS/PbTe phase boundary of nanometer scale is designed and it is demonstrated that its special strain distribution is in favor of achieving this goal. AbstractLead telluride (PbTe) has long been regarded as an excellent thermoelectric material at intermediate temperature range (573 –873 K); however, n-type PbTe's performance is always relatively inferior to its p-type counterpart mainly due to their different electronic band structures. In this work, an ultrahigh thermoelectric quality factor (µ/ κL ≈ 1.36 × 105 cm3 KJ−1 V−1) is reported in extra 0.3% Cu doped n-type (PbTe)0.9(PbS)0.1 as-cast ingots. Transmission electron microscopy (TEM) characterization reveals that excess PbS exists in PbTe matrix as strained endotaxial nanoprecipitates, which affect electrical and thermal conduction discriminately: (1) coherent PbTe/PbS lattice minimizes the interface scattering of charge carriers; (2) periodic strain centers at PbTe/PbS interface exhibit intensive strain contrast, which can strongly scatter heat-carrying phonons. Electron backscattered diffraction (EBSD) characterization illustrates very large PbTe grains ( ≈1 mm) in these as-cast ingots, ensuring an extremely low grain boundary scattering rate thus a very high charge carrier mobility. Eventually, a remarkably hig...

Source: Small - October 18, 2021 Category: Nanotechnology Authors: Shixuan Liu, Yong Yu, Di Wu, Xiao Xu, Xiaolian Chao, Zupei Yang, Jiaqing He Tags: Research Article Source Type: research