标题： 掺杂剂从整体角度抑制晶格热导率的作用 显示英文标题

标题： The role of lattice thermal conductivity suppression by dopants from a holistic perspective

摘要： 掺杂剂在改善电和热传输中起着重要作用。 从传统观点来看，掺杂剂通过向声子弛豫时间中添加点缺陷（PD）散射项来抑制晶格热导率kL，这一观点已被采用数十年。 在本研究中，我们提出了一种创新的视角来解决缺陷体系的kL问题——整体方法，即把掺杂剂和基质视为一个整体。 这种方法使我们能够通过缺陷体系的计算来明确处理缺陷的影响，例如由于掺杂剂的存在而导致的声子色散、声子-声子和电子-声子相互作用等的变化。 将缺陷MxNb1-xFeSb（M=V，Ti）与NbFeSb之间的kL降低作为整体方法的例子，得到了与实验结果相当的结果。 值得注意的是，轻元素掺杂剂也引发了避让交叉行为。 这可以通过一维原子链模型进一步合理解释。 质量与力常数不平衡通常会产生避让交叉的声子，数学上以类似于传统PD散射系数的方式产生，但在kL降低的方向上不同。 我们的工作为理解掺杂剂在材料热传输中的影响机制提供了另一种视角。 显示英文摘要

摘要： Dopants play an important role in improving electrical and thermal transport. In the traditional perspective, a dopant suppresses lattice thermal conductivity kL by adding point defect (PD) scattering term to the phonon relaxation time, which has been adopted for decades. In this study, we propose an innovative perspective to solve the kL of defective systems-the holistic approach, i.e., treating dopant and matrix as a holism. This approach allows us to handle the influences from defects explicitly by the calculations of defective systems, about their changed phonon dispersion, phonon-phonon and electron-phonon interaction, etc, due to the existence of dopants. The kL reduction between defective MxNb1-xFeSb (M=V, Ti) and NbFeSb is used as an example for the holistic approach, and comparable results with experiments are obtained. It is notable that light elemental dopants also induced the avoided-crossing behavior. It can be further rationalized by a one-dimensional atomic chain model. The mass and force constant imbalance generally generates the avoided-crossing phonons, mathematically in a similar way as the coefficients in traditional PD scattering, but along a different direction in kL reduction. Our work provides another perspective for understanding the mechanism of dopants influence in material's thermal transport.