Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
Nanoscale. 2018 Aug 9;10(31):15010-15022. doi: 10.1039/c8nr02234h.
Thermal management at solid interfaces presents a technological challenge for modern thermoelectric power generation. Here, we define a computational protocol to identify nanoscale structural features that can facilitate thermal transport in technologically important nanostructured materials. We consider the highly promising thermoelectric material, SrTiO3, where tilt grain boundaries lower thermal conductivity. The magnitude of the reduction is shown to depend on compositional and structural arrangements at the solid interface. Quantitative analysis indicates that layered nanostructures less than 10 nm will be required to significantly reduce the thermal conductivity below the bulk value, and it will be virtually independent of temperature for films less than 2 nm depending on the orientation with a reduction of thermal transport up to 75%. At the nanoscale, the vibrational response of nanostructures shows concerted vibrations between the grain boundary and inter-boundary regions. As the grain boundary acts markedly as a phonon quencher, we predict that any manipulation of nanostructures to further reduce thermal conductivity will be more beneficial if applied to the inter-boundary region. Our findings may be applied more widely to benefit other technological applications where efficient thermal transport is important.
固-固界面的热管理对现代热电发电技术提出了挑战。在这里，我们定义了一种计算方案，以确定可以促进技术上重要的纳米结构材料热传输的纳米级结构特征。我们考虑了很有前途的热电材料 SrTiO3，其中倾斜晶界会降低热导率。结果表明，降低的幅度取决于固-固界面的组成和结构排列。定量分析表明，要使热导率显著低于体值，需要小于 10nm 的层状纳米结构，而厚度小于 2nm 的薄膜则几乎与温度无关，其热输运的减少幅度可达 75%。在纳米尺度上，纳米结构的振动响应表现为晶界和晶界间区域之间的协同振动。由于晶界明显起到了声子猝灭剂的作用，我们预测，如果将任何进一步降低热导率的纳米结构处理应用于晶界间区域，将会更有益处。我们的发现可能会更广泛地应用于其他需要有效热传输的技术应用中。
