揭示 Half-Heusler 合金 ZrCo1-xIrxSb（x = 0、0.1 和 0.25）中的声子散射机制
Unravelling the phonon scattering mechanism in Half-Heusler alloys ZrCo1-xIrxSb (x = 0, 0.1, and 0.25)
AI总结：
本研究通过实验与 Klemens Callaway 模型分析 ZrCo1-xIrxSb，揭示 Ir 取代诱导的点缺陷与声子散射机制，显著降低晶格热导率且不改变载流子性质。
摘要：
了解导致 Half-Heusler 合金（HHA）晶格热导率（κL）降低的散射机制至关重要。在此背景下，我们深入研究了 ZrCo1-xIrxSb（x = 0、0.1 和 0.25）热导率的温度响应。对于 ZrCoSb，在 300 K 时 κL 约为 15.13 W/m-K，而在 ZrCo0.9Ir0.1Sb 中显著降至约 4.37 W/m-K。所观察到的降低归因于在取代为更重质量后声学声子模的软化和点缺陷散射。然而，由于散射参数相同，在 ZrCo0.75Ir0.25Sb 中未观察到 κL 进一步降低。这一点已基于 Klemens Callaway 模型得到阐明。此外，在母合金中，声子-声子散射机制在导热过程中发挥重要作用；而在 Ir 取代合金中，点缺陷散射（500 K 以下）和声子-声子散射（750 K 以上）是主导散射机制。ZrCo0.9Ir0.1Sb 在 950 K 时的最小 κL 约为 1.73 W/m-K，这是迄今为止 n 型 Zr 基 HHA 已报道的最低值。我们的研究表明，在 Co 位部分取代更重质量元素 Ir 可有效降低 n 型 ZrCoSb 的 κL，且不会改变载流子的性质。
英文摘要：
Insight about the scattering mechanisms responsible for reduction in the lattice thermal conductivity (\k{appa}L) in Half-Heusler alloys (HHA) is imperative. In this context, we have thoroughly investigated the temperature response of thermal conductivity of ZrCo1-xIrxSb (x = 0, 0.1 and 0.25). For ZrCoSb, \k{appa}L is found to be ~15.13 W/m-K at 300 K, which is drastically reduced to ~4.37 W/m-K in ZrCo0.9Ir0.1Sb. This observed reduction is ascribed to softening of acoustic phonon modes and point defect scattering, on substitution of heavier mass. However, no further reduction in \k{appa}L is observed in ZrCo0.75Ir0.25Sb, because of identical scattering parameter. This has been elucidated based on the Klemens Callaway model. Also, in the parent alloy, phonon-phonon scattering mechanism plays a significant role in heat conduction process, whereas in Ir substituted alloys, point defect scattering (below 500 K) and phonon-phonon scattering (above 750 K) are the dominant scattering mechanisms. The minimum \k{appa}L is found to be ~1.73 W/m-K (at 950 K) in ZrCo0.9Ir0.1Sb, which is the lowest reported value till now, for n-type Zr based HHA. Our studies indicate that partial substitution of heavier mass element Ir at Co-site effectively reduces the \k{appa}L of n-type ZrCoSb, without modifying the nature of charge carriers.
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