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P型Yb填充方钴矿材料塞贝克系数与晶格热导率的协同优化

Synergistic optimization of Seebeck coefficient and lattice thermal conductivity in p-type Yb-filled skutterudites

  • 摘要: 热电材料中电输运与热输运强烈耦合, 填充方钴矿材料可通过原子骨架进行电输运,而填充原子可散射声子,是典型的“电子晶体声子玻璃”。本研究针对p型方钴矿材料YbxFe3CoSb12系统研究了Yb填充量对其微观结构与热电输运性能的影响机制。XRD结果表明,所有样品均为立方CoSb3主相,当x ≥ 0.9时,FeSb2和Sb杂相明显减少,主相纯度显著提升。SEM观察显示Yb掺杂促进晶粒均匀化与致密化,EDS分析确认Yb元素分布的均匀性与掺杂水平密切相关。热电性能测试结果表明,适量Yb填充显著提升了Seebeck系数,在x = 1.0时于800 K下可达160 μV·K-1;同时,x = 0.9样品表现出优异的电导率与功率因子。热导率分析表明,Yb填充有效降低了晶格热导率,x = 1.0样品在800 K时κL降至1.2 W·m-1·K-1。最终,x = 1.0样品在750 K处实现最大zT值0.74,较已有文献提升约12%。本研究结果验证了Yb填充与熔融-热压协同工艺在提升p型方钴矿材料综合热电性能方面的协同优势,为高性能热电材料的结构调控与工程制备提供了有效路径。

     

    Abstract: In thermoelectric materials, electrical transport and thermal transport are strongly coupled. Filled skutterudite materials enable electrical transport through their atomic framework, while the filler atoms scatter phonons, making them typical "electron crystals-phonon glasses". This study systematically investigates the influence of Yb filling amount on the microstructure and thermoelectric transport properties of p-type skutterudite materials YbₓFe₃CoSb12. X-ray diffraction (XRD) results show that all samples exhibit a main phase with cubic skutterudite structure. When x ≥ 0.9, the impurity phases of FeSb₂ and Sb significantly decrease, and the purity of the main phase is remarkably improved. Scanning electron microscopy (SEM) observations reveal that Yb doping promotes grain homogenization and densification, and energy-dispersive X-ray spectroscopy (EDS) analysis confirms that the uniformity of Yb element distribution is closely related to the doping level. Thermoelectric property measurements indicate that appropriate Yb filling significantly enhances the Seebeck coefficient, reaching 160 μV·K⁻¹ at 800 K for x = 1.0 Meanwhile, the x = 0.9 sample exhibits excellent electrical conductivity and power factor. Thermal conductivity analysis shows that Yb filling effectively reduces the lattice thermal conductivity, with the lattice thermal conductivity (κL) of the x = 1.0 sample decreasing to 1.2 W·m⁻¹·K⁻¹ at 800 K. Ultimately, the x = 1.0 sample achieves a maximum zT value of 0.74 at 750 K, representing an improvement of approximately 12% compared to previously reported results. These findings validate the synergistic advantages of Yb filling combined with the melt-hot pressing process in enhancing the comprehensive thermoelectric performance of p-type skutterudite materials, providing an effective pathway for structural regulation and engineering preparation of high-performance thermoelectric materials.

     

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