Park Joonsuk, Bae Kiho, Kim Taeho Roy, Perez Christopher, Sood Aditya, Asheghi Mehdi, Goodson Kenneth E, Park Woosung
Department of Materials Science and Engineering Stanford University Stanford CA 94305 USA.
Department of Mechanical Engineering Stanford University Stanford CA 94305 USA.
Adv Sci (Weinh). 2020 Dec 21;8(3):2002876. doi: 10.1002/advs.202002876. eCollection 2021 Feb.
Transmission electron microscopy (TEM) is arguably the most important tool for atomic-scale material characterization. A significant portion of the energy of transmitted electrons is transferred to the material under study through inelastic scattering, causing inadvertent damage via ionization, radiolysis, and heating. In particular, heat generation complicates TEM observations as the local temperature can affect material properties. Here, the heat generation due to electron irradiation is quantified using both top-down and bottom-up approaches: direct temperature measurements using nanowatt calorimeters as well as the quantification of energy loss due to inelastic scattering events using electron energy loss spectroscopy. Combining both techniques, a microscopic model is developed for beam-induced heating and to identify the primary electron-to-heat conversion mechanism to be associated with valence electrons. Building on these results, the model provides guidelines to estimate temperature rise for general materials with reasonable accuracy. This study extends the ability to quantify thermal impact on materials down to the atomic scale.
透射电子显微镜（TEM）可以说是用于原子尺度材料表征的最重要工具。透射电子的很大一部分能量通过非弹性散射转移到被研究的材料上，通过电离、辐射分解和加热造成意外损伤。特别是，发热使TEM观察变得复杂，因为局部温度会影响材料特性。在这里，使用自上而下和自下而上的方法对电子辐照产生的热量进行了量化：使用纳瓦热量计进行直接温度测量，以及使用电子能量损失谱对非弹性散射事件导致的能量损失进行量化。结合这两种技术，开发了一个微观模型来研究束流诱导加热，并确定与价电子相关的主要电子-热转换机制。基于这些结果，该模型提供了以合理精度估算一般材料温度升高的指导方针。这项研究扩展了在原子尺度上量化热对材料影响的能力。
