Thickness-Independent Vibrational Thermal Conductance across Confined Solid-Solution Thin Films
Thickness-Independent Vibrational Thermal Conductance across Confined Solid-Solution Thin Films
复制标题
受限固溶体薄膜的与厚度无关的振动热导
DOI：
10.1021/acsami.0c20608
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发表时间：
2021
影响因子：
9.5
通讯作者：
Hopkins, Patrick E.
中科院分区：
文献类型：
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作者：
Giri, Ashutosh;Cheaito, Ramez;Gaskins, John T.;Mimura, Takanori;Brown-Shaklee, Harlan J.;Medlin, Douglas L.;Ihlefeld, Jon F.;Hopkins, Patrick E.
我们的实验表明，母材料之间的受限固溶体晶体薄膜之间的热导并不一定会导致薄膜几何形状上的热阻随着薄膜厚度的增加而增加，这与添加一种材料会增加总热阻的概念是相反的。在钛酸钙和(001)取向的钛酸锶两种母体钙钛矿材料之间生长了厚度系统变化的Ca0.5Sr0.5TiO3受限外延薄膜，并利用热反射技术精确测量了受限固溶体薄膜的热界电导，结果表明，在∼1~∼10 nm范围内，随着固溶体薄膜厚度的增加，热阻并没有显著增加。与沿热传播方向添加更多材料导致更大热阻的宏观热传输理解相反，我们的结果可能为通过计算预测的跨界面振动匹配的概念提供实验支持。这一概念是基于这样一个事实，即由于界面层而导致的可用载热振动的更好匹配可以导致较低的热边界电阻，从而导致通过在两个固体之间增加一层薄的“振动桥”层来驱动界面上的热边界电导的增强。
We experimentally show that the thermal conductance across confined solid-solution crystalline thin films between parent materials does not necessarily lead to an increase in thermal resistances across the thin-film geometries with increasing film thicknesses, which is counterintuitive to the notion that adding a material serves to increase the total thermal resistance. Confined thin epitaxial Ca0.5Sr0.5TiO3solid-solution films with systematically varying thicknesses in between two parent perovskite materials of calcium titanate and (001)-oriented strontium titanate are grown, and thermoreflectance techniques are used to accurately measure the thermal boundary conductance across the confined solid-solution films, showing that the thermal resistance does not substantially increase with the addition of solid-solution films with increasing thicknesses from ∼1 to ∼10 nm. Contrary to the macroscopic understanding of thermal transport where adding more material along the heat propagation direction leads to larger thermal resistances, our results potentially offer experimental support to the computationally predicted concept of vibrational matching across interfaces. This concept is based on the fact that a better match in the available heat-carrying vibrations due to an interfacial layer can lead to lower thermal boundary resistances, thus leading to an enhancement in thermal boundary conductance across interfaces driven by the addition of a thin “vibrational bridge” layer between two solids.