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首页> 外文期刊>Advanced Functional Materials >Parallel Dislocation Networks and Cottrell Atmospheres Reduce Thermal Conductivity of PbTe Thermoelectrics
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Parallel Dislocation Networks and Cottrell Atmospheres Reduce Thermal Conductivity of PbTe Thermoelectrics

机译：并行脱位网络和科特雷尔大气压降低PBTE热电的导热系数

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Dislocations play an important role in thermal transport by scattering phonons. Nevertheless, for materials with intrinsically low thermal conductivity, such as thermoelectrics, classical models require exceedingly high numbers of dislocations (10(12) cm(-2)) to further impede thermal transport. In this work, a significant reduction in thermal conductivity of Na0.025Eu0.03Pb0.945Te is demonstrated at a moderate dislocation density of 1 x 10(10) cm(-2). Further characteristics of dislocations, including their arrangement, orientation, and local chemistry are shown to be crucial to their phonon-scattering effect and are characterized by correlative microscopy techniques. Electron channeling contrast imaging reveals a uniform distribution of dislocations within individual grains, with parallel lines along four directions. Transmission electron microscopy (TEM) shows the parallel networks are edge-type and share the same Burgers vectors within each group. Atom probe tomography reveals the enrichment of dopant Na at dislocation cores, forming Cottrell atmospheres. The dislocation network is demonstrated to be stable during in situ heating in the TEM. Using the Callaway transport model, it is demonstrated that both parallel arrangement of dislocations and Cottrell atmospheres make dislocations more efficient in phonon scattering. These two mechanisms provide new avenues to lower the thermal conductivity in materials for thermal-insulating applications.
机译：脱位在散射声子中发挥着热传输中的重要作用。然而，对于具有本质低导热率的材料，例如热电，经典模型需要超过偏移量（＆ 10（12）cm（-2））以进一步妨碍热运输。在这项工作中，以1×10（10）厘米（-2）的中等位错密度来证明Na0.025eU0.03PB0.945Te的导热率显着降低。脱位的进一步特征，包括它们的排列，取向和局部化学被显示对它们的声子散射效应至关重要，并且以相关显微镜技术为特征。电子通道对比度成像显示单个颗粒内的位错分布，沿四个方向具有平行线。透射电子显微镜（TEM）显示并行网络是边缘型并在每个组内共享相同的汉堡矢量。原子探测断层扫描揭示了掺杂剂NA在位错核心，形成科特雷尔大气压的富集。位错网络被证明在TEM中原位加热期间是稳定的。使用Callaway传输模型，证明了脱位和Cottrell大气的并联排列使得脱位在声子散射中更有效。这两个机制提供了新的途径，以降低用于隔热应用的材料中的导热率。

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