The Impact of Nanostructuring on the Thermal Conductivity of Thermoelectric CoSb3
The Impact of Nanostructuring on the Thermal Conductivity of Thermoelectric CoSb3
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DOI：
10.1002/adfm.200400109
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发表时间：
2004-12
影响因子：
19
通讯作者：
M. Toprak;C. Stiewe;D. Platzek;S. Williams;L. Bertini;E. Müller;C. Gatti;Yu Zhang;Michael Rowe;M Muhammed
中科院分区：
文献类型：
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作者：
M. Toprak;C. Stiewe;D. Platzek;S. Williams;L. Bertini;E. Müller;C. Gatti;Yu Zhang;Michael Rowe;M Muhammed
纳米结构提供的高浓度晶界有望降低热电材料的热导率，这有利于热电性能图ZT的增加。采用一种新的化学合金化方法合成了纳米工程角脱石CoSb3。对CoSb3粉末进行不同时间的退火，得到了一组不同粒径的样品。然后将样品在不同条件下通过单轴压实成颗粒，并用于热电表征。在300 ~ 650 K的温度范围内，通过测量塞贝克系数和电导、导热系数来研究其输运性质。随着纳米区晶粒尺寸的减小，CoSb3的导热系数显著降低。对于平均晶粒尺寸为140 nm的材料，与单晶或高度退火的多晶材料相比，导热系数几乎降低了一个数量级。对于平均晶粒尺寸为220 nm的样品，在611 K时ZT值最高，为0.17。利用结合宏观有效介质方法和Kapitza阻力概念的模型，对观察到的导热系数随晶粒尺寸减小而减小的现象进行了量化。压实的样品表现出半导体典型的卡皮察电阻，与硅锗合金的电阻相当。
The high concentration of grain boundaries provided by nanostructuring is expected to lower the thermal conductivity of thermoelectric materials, which favors an increase in their thermoelectric figure‐of‐merit, ZT. A novel chemical alloying method has been used for the synthesis of nanoengineered‐skutterudite CoSb3. The CoSb3 powders were annealed for different durations to obtain a set of samples with different particle sizes. The samples were then compacted into pellets by uniaxial pressing under various conditions and used for the thermoelectric characterization. The transport properties were investigated by measuring the Seebeck coefficient and the electrical and thermal conductivities in the temperature range 300 K to 650 K. A substantial reduction in the thermal conductivity of CoSb3 was observed with decreasing grain size in the nanometer region. For an average grain size of 140 nm, the thermal conductivity was reduced by almost an order of magnitude compared to that of a single crystalline or highly annealed polycrystalline material. The highest ZT value obtained was 0.17 at 611 K for a sample with an average grain size of 220 nm. The observed decrease in the thermal conductivity with decreasing grain size is quantified using a model that combines the macroscopic effective medium approaches with the concept of the Kapitza resistance. The compacted samples exhibit Kapitza resistances typical of semiconductors and comparable to those of Si–Ge alloys.