Vacancy-induced dislocations within grains for high-performance PbSe thermoelectrics

• Published in: Nature communications Vol. 8; no. 1; p. 13828
• Main Authors: Chen, Zhiwei, Ge, Binghui, Li, Wen, Lin, Siqi, Shen, Jiawen, Chang, Yunjie, Hanus, Riley, Snyder, G. Jeffrey, Pei, Yanzhong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.01.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/1000; 639/301/299/2736; Civil engineering; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electrons; Grain boundaries; Heat conductivity; Humanities and Social Sciences; Materials science; multidisciplinary; Point defects; Science; Science (multidisciplinary); Semiconductors; Solid solutions; thermoelectrics; Beijing China; China
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms13828

To minimize the lattice thermal conductivity in thermoelectrics, strategies typically focus on the scattering of low-frequency phonons by interfaces and high-frequency phonons by point defects. In addition, scattering of mid-frequency phonons by dense dislocations, localized at the grain boundaries, has been shown to reduce the lattice thermal conductivity and improve the thermoelectric performance. Here we propose a vacancy engineering strategy to create dense dislocations in the grains. In Pb 1− x Sb 2 x /3 Se solid solutions, cation vacancies are intentionally introduced, where after thermal annealing the vacancies can annihilate through a number of mechanisms creating the desired dislocations homogeneously distributed within the grains. This leads to a lattice thermal conductivity as low as 0.4 Wm −1  K −1 and a high thermoelectric figure of merit, which can be explained by a dislocation scattering model. The vacancy engineering strategy used here should be equally applicable for solid solution thermoelectrics and provides a strategy for improving zT . In thermoelectric materials, dislocations at grain boundaries can be used to scatter midfrequency phonons. Here, Chen et al . use vacancy engineering and thermal annealing to generate dislocations homogeneously within the crystalline grains and obtain good figures of merit for PbSe-based thermoelectrics.