Two-channel model for ultralow thermal conductivity of crystalline Tl3VSe4
Two-channel model for ultralow thermal conductivity of crystalline Tl3VSe4
复制标题
DOI：
10.1126/science.aar8072
复制
发表时间：
2018-06-29
期刊：
影响因子：
56.9
通讯作者：
Lindsay, Lucas
中科院分区：
文献类型：
--
作者：
Mukhopadhyay, Saikat;Parker, David S.;Lindsay, Lucas
具有超低导热系数的固体材料作为隔热材料的热障涂层或用于能量转换的热电材料具有很大的应用价值。然而，晶格热导率(Kappa)的理论极限还不清楚。在典型的晶体中，声子图像是有效的，而最低的卡伯值出现在高度无序的材料中，在那里图像失效，热量被认为是通过在不相关的振荡器之间的随机行走来携带的。在这里，我们确定了一个简单的晶体，T13VSe4，其计算的声子kappa[0.16瓦/米-开尔文(W/m-K)]是我们在300K测得的kappa(0.30W/m-K)的一半，接近无序Kappa值，尽管拉曼光谱、比热和kappa的温度依赖关系揭示了典型的声子特征。加入基于非关联振子的输运分量解释了测量的kappa，并表明对于具有超低kappa的晶体，双通道模型是必要的。
Solids with ultralow thermal conductivity are of great interest as thermal barrier coatings for insulation or thermoelectrics for energy conversion. However, the theoretical limits of lattice thermal conductivity (kappa) are unclear. In typical crystals a phonon picture is valid, whereas lowest kappa values occur in highly disordered materials where this picture fails and heat is supposedly carried by random walk among uncorrelated oscillators. Here we identify a simple crystal, Tl3VSe4, with a calculated phonon kappa [0.16 Watts per meter-Kelvin (W/m-K)] one-half that of our measured kappa (0.30 W/m-K) at 300 K, approaching disorder kappa values, although Raman spectra, specific heat, and temperature dependence of kappa reveal typical phonon characteristics. Adding a transport component based on uncorrelated oscillators explains the measured kappa and suggests that a two-channel model is necessary for crystals with ultralow kappa.