Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China.
Nat Commun. 2017 Jan 4;8:13828. 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 PbSbSe 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 K 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.
为了最小化热电材料中的晶格热导率，通常采用的策略是通过界面来散射低频声子，通过点缺陷来散射高频声子。此外，通过在晶界处密集的位错（局部化）来散射中频声子，也可以降低晶格热导率并改善热电性能。在这里，我们提出了一种空位工程策略，即在 PbSbSe 固溶体中引入阳离子空位，然后通过热退火使空位通过多种机制消除，从而在晶粒内均匀地产生所需的位错。这导致晶格热导率低至 0.4 WmK 和高热电优值，可以通过位错散射模型来解释。此处使用的空位工程策略应同样适用于固溶体型热电材料，并为提高 zT 提供了一种策略。
