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[资源] 2012年9月Nature关于热电材料最新文献High-performance bulk TE with 分级结构

索引：Biswas, K., J. He, et al. (2012). "High-performance bulk thermoelectrics with all-scale hierarchical architectures." Nature 489(7416): 414-418

摘要：With about two-thirds of all used energy being lost as waste heat,
there is a compelling need for high-performance thermoelectric
materials that can directly and reversibly convert heat to electrical
energy.However, the practical realization of thermoelectricmaterials
is limited by their hitherto low figure of merit,ZT, which governs the
Carnot efficiency according to the second law of thermodynamics.
The recent successful strategy of nanostructuring to reduce thermal
conductivity has achieved record-highZT values in the range 1.5–1.8
at 750–900 kelvin1–3, but still falls short of the generally desired
threshold value of 2. Nanostructures in bulk thermoelectrics allow
effective phonon scattering of a significant portion of the phonon
spectrum, but phonons with long mean free paths remain largely
unaffected. Here we show that heat-carrying phonons with long
mean free paths can be scattered by controlling and fine-tuning the
mesoscale architecture of nanostructured thermoelectric materials.
Thus, by consideringsourcesof scattering on all relevant length scales
in a hierarchical fashion—from atomic-scale lattice disorder and
nanoscale endotaxial precipitates to mesoscale grain boundaries—
we achieve the maximum reduction in lattice thermal conductivity
and a large enhancement in the thermoelectric performance of PbTe.
By taking such a panoscopic approach to the scattering of heatcarrying
phonons across integrated length scales, we go beyond
nanostructuring and demonstrate a ZT value of 2.2 at 915 kelvin
in p-type PbTe endotaxially nanostructured with SrTe at a concentration
of 4 mole per cent and mesostructured with powder
processing and spark plasma sintering. This increase in ZT beyond
the threshold of 2 highlights the role of, and need for, multiscale
hierarchical architecture in controlling phonon scattering in bulk
thermoelectrics, and offers a realistic prospect of the recovery of a
significant portion of waste heat.

实验方法：Several samples of PbTe–SrTe(0–4 mol%) doped with 2 mol% Na were
synthesized first in the form of bulk ingots by melting at 1,323K over 10 h,
quenching to room temperature (297 K), followed by powder processing
(Retsch RM200, Retsch GmbH) and spark plasma sintering (SPS 10-4, Thermal
Technology LLC) at 823K for 10 min under an axial pressure of 60MPa in an
argon atmosphere (supplementary, experimental). The s and S were measured
simultaneously in a helium atmosphere at temperatures ranging from room temperature
to about 923K on a ULVAC-RIKO ZEM-3 instrument system. We
determined carrier concentrations using measurements of Hall coefficients at
room temperature with a home-built system in applied magnetic fields ranging
from 0 to 1.25 T. The thermal diffusivity, D, was directly measured in the temperature
range 300–923K by using the laser flash diffusivity method in a commercial
Netzsch LFA-457 instrument. The thermal diffusivity was measured along the
same direction as was the electrical transport. The heat capacity, Cp, was
determined on the basis of previous reported experimental literature for PbTe
(refs 11, 29). The total thermal conductivity was calculated using the formula
ktotal5DCpr, where r is the sample density, measured by gas pycnometer
(Micromeritics AccuPyc 1340).

引文29篇。

附件2为Endnote索引。

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附件 1 : Biswas,K.,J.He,etal.(2012).High-performancebulkthermoelectricswithall-scalehierarchicalarchitectures.Nature489(7416)414-418-p-.pdf

2012-09-28 23:03:02, 2.07 M