期刊
ENERGY & ENVIRONMENTAL SCIENCE
卷 8, 期 7, 页码 2056-2068出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5ee01147g
关键词
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资金
- South University of Science and Technology of China
- Science, Technology and Innovation Commission of Shenzhen Municipality [JCYJ20140612140151884]
- NSFC [11404160, 51202008]
- Beihang University
- Recruitment Program for Young Professionals
- Postdoctoral Science Foundation of China [2013M540037]
- Revolutionary Materials for Solid State Energy Conversion, an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences [DE-SC0001054]
Lead chalcogenides are dominant thermoelectric materials in the medium-temperature range due to their highly favorable electronic band structures and low thermal conductivities. An important system is the PbTe-PbS pseudo-binary, and its low thermal conductivity originates largely from the coexistence of both alloying and nanostructuring through phase-separation. To better understand the competition between the alloying and phase separation and its pronounced effects on the thermoelectric performance in PbTe-PbS, we systematically studied, via transmission electron microscopy (TEM) observations and theoretical calculations, the samples of Spark Plasma Sintered (SPSed) 3 at% Na-doped (PbTe)(1-x)(PbS)(x) with x = 10%, 15%, 20%, 25%, 30% and 35%. The highest figure of merit, viz., ZT similar to 2.3 was obtained at 923 K, when the PbS phase-fraction, x, was 20%, which corresponds to the lowest lattice thermal conductivity of the series. The consistently lower lattice thermal conductivities in the SPSed samples as compared with the corresponding ingots originates from the mesostructured nature of the former, which contributes significantly to their superior ZT. We also studied the onset of carrier concentration modulation at similar to 600 K, which leads to the observed saturation of electrical transport properties due to the diffusion and re-dissolution of excessive Na into the PbTe-PbS matrix. This carrier concentration modulation is equally crucial to achieve very high power factors (up to 26.5 mW cm(-1) K-2 at 623 K) and outstanding thermoelectric performances in SPSed PbTe-PbS binaries.
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