Ghosh Sanyukta, Shankar Gyan, Karati Anirudha, Werbach Katharina, Rogl Gerda, Rogl Peter, Bauer Ernst, Murty B S, Suwas Satyam, Mallik Ramesh Chandra
Thermoelectric Materials and Devices Laboratory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India.
ACS Appl Mater Interfaces. 2020 Oct 28;12(43):48729-48740. doi: 10.1021/acsami.0c17254. Epub 2020 Oct 19.
The thermoelectric efficiency of skutterudite materials can be improved by lowering the lattice thermal conductivity via the uniform dispersion of a nanosized second phase in the matrix of filled CoSb. In this work, nanocomposites of BaCoSb and InSb were synthesized using ball-milling and spark plasma sintering. The thermoelectric transport properties were studied from 4.2 to 773 K. The InSb nanoparticles of ∼20 nm were found to be dispersed in the BaCoSb grains with a few larger grains of about 10 μm due to the agglomeration of the InSb nanoparticles. The +2 oxidation state of Ba in CoSb resulted in a low electrical resistivity, ρ, value of the matrix. The enhancement of the Seebeck coefficient, , and the electrical resistivity values of BaCoSb with the addition of InSb can be credited to the energy-filtering effect of electrons with low energy at the interfaces. The power factor of the composites could not be enhanced compared to the matrix because of the very high ρ value. A minimum possible lattice thermal conductivity (0.45 W/m·K at 773 K) was achieved due to the combined effect of rattling of Ba atoms in the voids and enhanced phonon scattering at the interfaces induced by nanosized InSb particles. As a result, the (InSb) + BaCoSb composite exhibited improved thermoelectric properties with the highest of 1.4 at 773 K and improved mechanical properties with a higher hardness, higher Young's modulus, and lower brittleness.
通过在填充CoSb基体中均匀分散纳米尺寸的第二相来降低晶格热导率，可以提高方钴矿材料的热电效率。在这项工作中，使用球磨和放电等离子体烧结合成了BaCoSb和InSb的纳米复合材料。研究了4.2至773 K范围内的热电输运性质。由于InSb纳米颗粒的团聚，发现约20 nm的InSb纳米颗粒分散在BaCoSb晶粒中，还有一些约10μm的较大晶粒。CoSb中Ba的 +2氧化态导致基体的低电阻率ρ值。添加InSb后，BaCoSb的塞贝克系数和电阻率值的提高可归因于界面处低能电子的能量过滤效应。由于ρ值非常高，复合材料的功率因子无法比基体提高。由于Ba原子在空隙中的晃动以及纳米尺寸InSb颗粒在界面处引起的声子散射增强的综合作用，实现了最低可能的晶格热导率（773 K时为0.45 W/m·K）。结果，(InSb)+BaCoSb复合材料表现出改善的热电性能，在773 K时最高ZT为1.4，并且具有更高的硬度、更高的杨氏模量和更低的脆性，从而改善了机械性能。
