Abstract 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 ~ 0.7 at 860 K has been realized with a pioneering (ZT)average ~ 0.34 in p-type CoSb3 co-doped by Fe and Bi at an optimal composition of Fe0.25Co0.75Sb2.995Bi0.005. 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 first-principles 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.

中文翻译：

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采用等电子双掺杂优化 Fe0.25Co0.75Sb3 方钴矿的电和热传输性能

摘要 未填充的 CoSb3 基方钴矿在热电 (TE) 器件中的实际应用受到限制，主要是因为它们的双极传导行为不利于热电性能。在目前的研究中，在 860 K 处实现了峰值 TE 品质因数 (ZT)max ~ 0.7，在由 Fe 和 Bi 以最佳组成共掺杂的 p 型 CoSb3 中的开创性 (ZT) 平均值 ~ 0.34 Fe0.25Co0.75Sb2.995Bi0.005。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 特性测量结果表明 CoSb3 中 Co 位的 Fe 掺杂导致单极 p 型传导，而 Sb 位的 Bi 取代有助于通过增强的点缺陷引起的声子散射降低热导率。合成的样品被表征为相，使用 X 射线衍射、场发射扫描电子显微镜和透射电子显微镜观察形貌和结构，在此基础上还讨论了合成样品的一些 TE 特性。此外，还通过实验和理论研究了磁熵对 TE 性能的影响。基于第一性原理的密度泛函理论已被用于电子能带结构、电输运特性和磁矩的理论计算，发现它们与实验观察相当吻合。还通过实验和理论研究了磁熵对 TE 性能的影响。基于第一性原理的密度泛函理论已被用于电子能带结构、电输运特性和磁矩的理论计算，发现它们与实验观察相当吻合。还通过实验和理论研究了磁熵对 TE 性能的影响。基于第一性原理的密度泛函理论已被用于电子能带结构、电输运特性和磁矩的理论计算，发现它们与实验观察相当吻合。