Optimization of electrical and thermal transport properties of Fe0.25Co0.75Sb3 Skutterudite employing the isoelectronic Bi-doping
Optimization of electrical and thermal transport properties of Fe0.25Co0.75Sb3 Skutterudite employing the isoelectronic Bi-doping
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DOI：
10.1016/j.intermet.2020.106796
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发表时间：
2020-08-01
期刊：
影响因子：
4.4
通讯作者：
Dhar, Ajay
中科院分区：
文献类型：
--
作者：
Bhardwaj, Ruchi;Johari, Kishor Kumar;Dhar, Ajay
未填充的CoSb 3基方钴矿用于热电（TE）器件的实际应用受到限制，主要是由于其双极导电行为，这对TE性能是不利的。在目前的研究中，在Fe（0.25）Co（0.75）Sb（2.99）5Bi（0.005）的最佳成分下，在Fe和Bi共掺杂的p型CoSb 3中，在860 K下实现了类似于0.7的峰值TE优值（ZT）（max），其中开创性的（ZT）（平均值）类似于0.34。该合金的合成路线是电弧熔炼和放电等离子烧结相结合。TE性质的测量结果表明，Fe在Co位的掺杂导致了CoSb 3的单极p型导电，而Bi在Sb位的掺杂通过增强点缺陷诱导的声子散射降低了热导率。利用X射线衍射、场发射扫描电子显微镜和透射电子显微镜对合成样品的物相、形貌和结构进行了表征，并在此基础上讨论了合成样品的热电性能。此外，还从实验和理论上研究了磁熵对TE性能的影响。基于第一性原理的密度泛函理论已被用于理论计算的电子能带结构，电输运性质和磁矩，这被发现是在公平的协议与实验观察。
The practical applications of unfilled CoSb3-based Skutterudites for thermoelectric (TE) devices have been limited primarily owing to their bipolar conduction behaviour, which is detrimental for the TE performance. In the present studies, a peak TE figure-of-merit (ZT)(max) similar to 0.7 at 860 K has been realized with a pioneering (ZT)(average) similar to 0.34 in p-type CoSb3 co-doped by Fe and Bi at an optimal composition of Fe(0.25)Co(0.75)Sb(2.99)5Bi(0.005). The synthesis route for the alloy was the combination of arc melting and the spark plasma sintering. The TE properties measurement results suggest that the Fe doping at the Co site in CoSb3 lead to the unipolar p-type conduction while Bi substitution at Sb site helps in reducing the thermal conductivity via enhanced point defect induced phonon scattering. The synthesized samples were characterised for phase, morphology and structure using X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy, based on which some TE properties of the synthesized samples have also been discussed. In addition, the effect of magnetic entropy on the TE performance has also been studied experimentally as well as theoretically. The firstprinciples based density functional theory has been employed for the theoretical calculation of the electronic band-structure, electrical transport properties and the magnetic moment, which are found to be in fair agreement with the experimental observations.