论文标题
各向异性热导率张量测量使用梁挡群频域热素（BO-FDTR）用于缺乏平面对称性的材料
Anisotropic thermal conductivity tensor measurements using beam-offset frequency domain thermoreflectance (BO-FDTR) for materials lacking in-plane symmetry
论文作者
论文摘要
许多材料具有各向异性导热率，具有不同的应用，例如晶体管，热电和激光增益培养基。然而，测量此类材料的热导率张量仍然是一个挑战，特别是对于缺乏平面对称性的材料（即横向各向异性材料）。本文通过扩展了横梁偏移频率域热反射率（BO-FDTR）方法，该方法展示了用于横向各向异性材料的热导率张量测量，该方法先前限制为横向各向同性材料。广泛的灵敏度分析用于确定适当的加热频率和光束偏移量以提取各种张量元件。通过将光束偏移量测量值组合到不同样品方向以重建完整的平面内导热率张量，在横向各向异性材料X-Cut Quartz（<110>α-SIO2）上展示了新技术。该技术还通过测量两种横向各向同性材料，蓝宝石和高度定向的热解石墨（HOPG）来验证。各向异性测量值在存在时正确识别各向同性方向时表现出非常好的自偶然性，蓝宝石的残留各向异性误差低于4％，而Hopg和Quartz则为2％。最后，一项计算案例研究（模拟实验）显示了如何仅从单个样品方向获得具有高平面各向异性的虚拟材料的任意内部热导率张量，而不是从单个样品方向获得，而不是像X-Cut Quartz上的实验一样多种取向。
Many materials have anisotropic thermal conductivity, with diverse applications such as transistors, thermoelectrics, and laser gain media. Yet measuring the thermal conductivity tensor of such materials remains a challenge, particularly for materials lacking in-plane symmetry (i.e., transversely anisotropic materials). This paper demonstrates thermal conductivity tensor measurements for transversely anisotropic materials, by extending beam-offset frequency-domain thermoreflectance (BO-FDTR) methods which had previously been limited to transversely isotropic materials. Extensive sensitivity analysis is used to determine an appropriate range of heating frequencies and beam offsets to extract various tensor elements. The new technique is demonstrated on a model transversely anisotropic material, x-cut quartz (<110> α-SiO2), by combining beam offset measurements from different sample orientations to reconstruct the full in-plane thermal conductivity tensor. The technique is also validated by measurements on two transversely isotropic materials, sapphire and highly oriented pyrolytic graphite (HOPG). The anisotropic measurements demonstrated very good self-consistency in correctly identifying isotropic directions when present, with residual anisotropy errors below 4% for sapphire and 2% for HOPG and quartz. Finally, a computational case study (simulated experiment) shows how the arbitrary in-plane thermal conductivity tensor of a fictitious material with high in-plane anisotropy can in principle be obtained from only a single sample orientation, rather than multiple orientations like the experiments on x-cut quartz.
