Lattice thermal conductivity of embedded nanoparticle composites: the role of particle size distribution
Lattice thermal conductivity of embedded nanoparticle composites: the role of particle size distribution
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DOI：
10.1088/1361-6528/ad06d6
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发表时间：
2023-11
期刊：
影响因子：
3.5
通讯作者：
Theodore Maranets;Haoran Cui;Yan Wang
中科院分区：
文献类型：
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作者：
Theodore Maranets;Haoran Cui;Yan Wang
嵌入晶体固体中的纳米颗粒作为杂质声子散射中心，降低晶格导热性，这是热电应用的理想结果。大多数纳米颗粒负载复合材料的热输运研究都假设纳米颗粒具有单一尺寸。如果存在纳米颗粒大小的分布，热导率是如何受到影响的？此外，是否存在最佳的纳米颗粒尺寸分布以最小化导热系数？在这项工作中，我们通过分子动力学方法研究了纳米颗粒负载复合材料的导热性，该方法比以前使用的分析理论更严格地自然捕获声子散射过程。从系统的各种纳米粒子构型的热输运模拟中，我们经验地阐述了纳米粒子的尺寸分布、粒子数密度和体积分数如何影响晶格导热性。我们发现，当体积分数低于10%时，颗粒数密度是迄今为止对导热性影响最大的因素，而当体积分数高于10%时，与体积分数相比，粒径分布和颗粒数密度的影响最小。事实上，在比较具有相同粒子数密度和体积分数的构型时，单个纳米颗粒尺寸的晶格热导率可能低于一个尺寸分布的晶格热导率，这与单一尺寸对声子输运的衰减小于一个尺寸谱的直觉相矛盾。随机合金可以被认为是具有最大颗粒数密度的单一尺寸构型，其中纳米颗粒尺寸等于晶格常数，在体积分数低于10%时，其导热系数降低效果最好。我们得出的结论是，纳米颗粒尺寸分布对晶格导热性的影响较小，而颗粒数量密度和体积分数是制造纳米颗粒负载复合材料时应考虑的更重要的因素，以潜在地改善热电性能。
Nanoparticles embedded within a crystalline solid serve as impurity phonon scattering centers that reduce lattice thermal conductivity, a desirable result for thermoelectric applications. Most studies of thermal transport in nanoparticle-laden composite materials have assumed the nanoparticles to possess a single size. If there is a distribution of nanoparticle sizes, how is thermal conductivity affected? Moreover, is there a best nanoparticle size distribution to minimize thermal conductivity? In this work, we study the thermal conductivity of nanoparticle-laden composites through a molecular dynamics approach which naturally captures phonon scattering processes more rigorously than previously used analytical theories. From thermal transport simulations of a systematic variety of nanoparticle configurations, we empirically formulate how nanoparticle size distribution, particle number density, and volume fraction affect the lattice thermal conductivity. We find at volume fractions below 10%, the particle number density is by far the most impactful factor on thermal conductivity and at fractions above 10%, the effect of the size distribution and number density is minimal compared to the volume fraction. In fact, upon comparisons of configurations with the same particle number density and volume fractions, the lattice thermal conductivity of a single nanoparticle size can be lower than that of a size distribution which contradicts intuitions that a single size would attenuate phonon transport less than a spectrum of sizes. The random alloy, which can be considered as a single size configuration of maximum particle number density where the nanoparticle size is equal to the lattice constant, is the most performant in thermal conductivity reduction at volume fractions below 10%. We conclude that nanoparticle size distribution only plays a minor role in affecting lattice thermal conductivity with the particle number density and volume fraction being the more significant factors that should be considered in fabrication of nanoparticle-laden composites for potential improved thermoelectric performance.