In-plane thermal conductivities of small-scale samples are hard to measure, especially for the lowly conductive ones and those lacking in-plane symmetry (i.e., transversely anisotropic materials). State-of-the-art pump-probe techniques including both the time-domain and the frequency-domain thermoreflectance (TDTR and FDTR) are advantageous in measuring the thermal conductivity of small-scale samples, and various advanced TDTR and FDTR techniques have been developed to measure transversely anisotropic materials. However, the measurable in-plane thermal conductivity (k_in) is usually limited to be >10 W/(m K). In this work, a new spatial-scan thermoreflectance (SSTR) method has been developed to measure a broad range of k_in of millimeter-scale small samples, including those lacking in-plane symmetry, extending the current limit of the measurable k_in to as low as 1 W/(m K). This SSTR method establishes a new scheme of measurements using the optimized laser spot size and modulation frequency and a new scheme of data processing, enabling measurements of in-plane thermal conductivity tensors of a broad range of k_in values with both high accuracy and ease of operation. Some details such as the requirement on the sample geometry, the effect of the transducer layer, and the effect of heat loss are also discussed. As a verification, the k_in of some transversely isotropic reference samples with a wide range of k_in values including fused silica, sapphire, silicon, and highly ordered pyrolytic graphite (HOPG) have been measured using this new SSTR method. The measured k_in agree perfectly well with the literature values with a typical uncertainty of 5%. As a demonstration of the unique capability of this method, the in-plane thermal conductivity tensor of x-cut quartz, an in-plane anisotropic material, has also been measured.
Length Dependence thermal conductivity of Zinc-Selenide (ZnSe) and Zinc Telluride (ZnTe)- A combined first principles and Frequency Domain Thermoreflectance (FDTR) study
Thermal Conductivity of Oxide Tunnel Barriers in Magnetic Tunnel Junctions Measured by Ultrafast Thermoreflectance and Magneto-optic Kerr Effect Thermometry
磁隧道结中自旋相关的电荷输运可以通过温度梯度来控制，这可以用于自旋电子学和自旋热电子学应用。热致现象的评价需要了解邻近铁磁（FM）引线的氧化物隧道势垒的温差。然而，准确测量仅由几个原子层组成的氧化物隧道势垒的热性质是具有挑战性的。在这项工作中，我们实验询问的温度演变的Ru/氧化物/FM/种子/MgO（氧化物=MgO，MgAl 2 O 4; FM=Co，CoFeB;种子=Pt，Ta）结构具有垂直磁各向异性使用超快测温。Ru层是光学厚度和超快激光脉冲加热，随后的温度变化监测使用Ru和磁光克尔效应（MOKE）的FM层的热反射。我们使用二次MOKE独立测量Co和CoFeB磁性的响应时间，并获得Co的τem=0.2 ps，CoFeB的τem = 2 ps。这些时间尺度比通过氧化物隧道势垒的热传输的时间尺度短得多，其发生在10-3000 ps。我们确定的MgO和MgAl 2 O 4隧道势垒的有效热导率在0.4-0.6 W m-1 K-1的范围内，可比的Ru/氧化物和氧化物/FM接口的串联电导的估计和一个数量级小于MgO薄膜的热导率。我们发现，在隧道势垒附近的电子-声子的热导是只有5-12倍的氧化物隧道势垒的热导大。因此，电子温度的下降比穿过隧道势垒的声子温度的下降大大约20-30%。
Simultaneous Measurement of Thermal Conductivity, Heat Capacity, and Interfacial Thermal Conductance by Leveraging Negative Delay-Time Data in Time-Domain Thermoreflectance
Simultaneous measurement of pressure-dependent bulk and interfacial thermal properties in thermal interface materials using square-pulsed source thermoreflectance
School of Energy and Power Engineering, Huazhong University of Science and Technology（华中科技大学能源与动力工程学院）
Beam-Offset Thermoreflectance with Bayesian Optimization to Measure the Anisotropic Thermal Properties of Semiconductor Superlattices
Nicolaus Copernicus University in Toruń（托伦哥白尼大学）；Ruhr-University Bochum（波鸿鲁尔大学）；China University of Petroleum, Beijing（中国石油大学（北京））；CNRS, Institut des Nanosciences de Paris, University of Sorbonne（法国国家科学研究中心，巴黎纳米科学研究所，索邦大学）
A Coupled Thermoreflectance Thermography Experimental System and Ultra-Fast Adaptive Computational Engine for the Complete Thermal Characterization of Three-Dimensional Electronic Devices: Validation
Ultralow and Tunable Thermal Conductivity of Parylene C for Thermal Insulation in Advanced Packaging
School of Software & Microelectronics, Peking University（北京大学软件与微电子学院）；School of Integrated Circuits and Beijing Advanced Innovation Center for Integrated Circuits, Peking University（北京大学集成电路学院及北京集成电路先进创新中心）
Thermal conductivity reduction in (Zr$_{0.25}$Ta$_{0.25}$Nb$_{0.25}$Ti$_{0.25}$)C high entropy carbide from extrinsic lattice defects
具有随机分布的多个主阳离子的高熵碳化物陶瓷显示出高的温度稳定性、低的热导率和可能的耐辐射性。虽然化学无序已被证明可以抑制这些材料的热导率，但很少有人研究额外的外部产生的结构缺陷对热传输的影响。在此，（Zr $_{0.25}$ Ta $_{0.25}$ Nb $_{0.25}$ Ti $_{0.25}$）C暴露于Zr离子以产生微米级结构缺陷承载层。使用激光热反射测量晶格热输运的减少。不同注入温度下的电导率变化表明位错环对声子散射的贡献很小，而纳米级缺陷则是有效的散射体，为热工程提供了一条途径。
Measurements and Numerical Calculations of Thermal Conductivity to Evaluate the Quality of β-Gallium Oxide Thin Films Grown on Sapphire and Silicon Carbide by Molecular Beam Epitaxy
报道了一种在c面蓝宝石和4 H-SiC衬底上用分子束外延（MBE）生长的β-Ga 2 O3薄膜的低热导率研究方法。我们将实验值与数值预测进行比较，以解释薄膜中边界散射和缺陷的影响。我们使用时域热反射（TDTR）进行实验，密度泛函理论和玻尔兹曼输运方程的热导率计算，和扩散失配模型TBC预测。实验的热导率约为3倍小于那些计算的类似大小的完美的Ga 2 O 3晶体。当在计算中考虑晶界、镓和氧空位以及堆垛层错的存在时，存在约1%的镓空位和106个缺陷/cm的堆垛层错密度的晶体是热导率更接近实验结果的晶体。我们的分析表明，不同类型的缺陷存在于Ga 2 O3晶体，可用于通过减少这些缺陷，从而产生具有更高的热导率的材料，以提高MBE生长的样品的质量的水平。
Thermal conductivity of intercalation, conversion, and alloying lithium-ion battery electrode materials as function of their state of charge
在插入和取出锂时，对于电化学能量储存重要的材料可以经历热导率（$Λ$）和弹性模量（$\it M$）的变化。这些变化是由于演化的固有的热载流子寿命和原子间的键合强度与电极材料的结构转变具有不同程度的可逆性。利用原位时域热反射技术和皮秒声学技术，系统研究了电极材料在循环过程中的转化、嵌入和合金化过程中的$Λ$和$\it M$。插层V $_{2}$ O $_{5}$和TiO $_{2}$表现出非单调可逆$Λ$和$\it M$切换高达1.8倍（$Λ$）和1.5倍（$\it M$）作为锂含量的函数。在第一次锂化时，转化的Fe $_{2}$ O $_{3}$和NiO在$Λ$和$\it M$中经历不可逆衰变。合金化Sb显示出$Λ$在脱锂状态（18 W m $^{-1}$ K $^{-1}$）和锂化状态（<1 W m $^{-1}$ K $^{-1}$）之间的最大和部分可逆的数量级的量值切换。不可逆的$Λ$归因于循环过程中大量体积变化导致的结构降解和粉碎。这些发现为电池设计的重要性循环过程中电极材料的热和机械性能演变提供了新的理解，并且还指出了形成具有热切换性能的材料的途径。
Thermal conductivity of rare-earth scandates in comparison to other oxidic substrate crystals
比较了DyScO $_3$、TbScO $_3$和GdScO $_3$与La $_{0.29}$ Sr $_{0.71}$ Al $_{0.65}$ Ta $_{0.35}$ O $_3$（LSAT）和蓝宝石的高温热性能。为了计算热导率，分别通过差示扫描量热法和激光闪光技术测量热容和热扩散率。DyScO $_3$和TbScO $_3$在900 ° K以上显示出热导率的非典型上升，而对于GdScO $_3$、LSAT和蓝宝石，可以观察到在升高的温度下的预期下降。这些结果导致一种新的类型的热传输的建议迁移离子。
