Trivedi Vikrant, Battabyal Manjusha, Perumal Suresh, Chauhan Avnee, Satapathy Dillip K, Murty Budaraju Srinivasa, Gopalan Raghavan
Centre for Automotive Energy Materials, International Advanced Research Center for Powder Metallurgy and New Materials, IIT Madras Research Park, Taramani, Chennai 600113, India.
Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras, Chennai 6000036, India.
ACS Omega. 2021 Jan 28;6(5):3900-3909. doi: 10.1021/acsomega.0c05740. eCollection 2021 Feb 9.
We report a systematic investigation of the microstructure and thermoelectric properties of refractory element-filled nanostructured CoSb skutterudites. The refractory tantalum (Ta) metal-filled CoSb samples (Ta CoSb ( = 0, 0.4, 0.6, and 0.8)) are synthesized using a solid-state synthesis route. All the samples are composed of a single skutterudite phase. Meanwhile, nanometer-sized equiaxed grains are present in the TaCoSb and TaCoSb samples, and bimodal distributions of equiaxed grains and elongated grains are observed in TaCoSb and TaCoSb samples. The dominant carrier type changes from electrons (n-type) to holes (p-type) with an increase in Ta concentration in the samples. The power factor of the TaCoSb sample is increased to 2.12 mW/mK at 623 K due to the 10-fold reduction in electrical resistivity. The lowest lattice thermal conductivity observed for TaCoSb indicates the rattling action of Ta atoms and grain boundary scattering. Rietveld refinement of XRD data and the analysis of lattice thermal conductivity data using the Debye model confirm that Ta occupies at the voids as well as the Co site. The figure of merit (ZT) of ∼0.4 is obtained in the TaCoSb sample, which is comparable to single metal-filled p-type skutterudites reported to date. The thermoelectric properties of the refractory Ta metal-filled skutterudites might be useful to achieve both n-type and p-type thermoelectric legs using a single filler atom and could be one of replacements of the rare earth-filled skutterudites with improved thermoelectric properties.
我们报告了对难熔元素填充的纳米结构钴锑方钴矿的微观结构和热电性能的系统研究。采用固态合成路线合成了难熔金属钽（Ta）填充的CoSb样品（Ta CoSb（ = 0、0.4、0.6和0.8））。所有样品均由单一的方钴矿相组成。同时，TaCoSb和TaCoSb样品中存在纳米尺寸的等轴晶粒，而在TaCoSb和TaCoSb样品中观察到等轴晶粒和拉长晶粒的双峰分布。随着样品中Ta浓度的增加，主导载流子类型从电子（n型）变为空穴（p型）。由于电阻率降低了10倍，TaCoSb样品在623 K时的功率因数提高到2.12 mW/mK。TaCoSb观察到的最低晶格热导率表明Ta原子的晃动作用和晶界散射。XRD数据的Rietveld精修以及使用德拜模型对晶格热导率数据的分析证实，Ta占据了空隙以及Co位点。TaCoSb样品的优值（ZT）约为0.4，与迄今报道的单金属填充p型方钴矿相当。难熔金属Ta填充的方钴矿的热电性能可能有助于使用单个填充原子实现n型和p型热电腿，并且可能是具有改进热电性能的稀土填充方钴矿的替代品之一。
