AI 中文总结
本研究利用同步TXM与XRD在PAL-XFEL上观测Bi₂Se₃的累积X射线损伤，明确其两种损伤机制，揭示晶界形成的加速作用，建立跨尺度辐射损伤研究方法。
AI 中文摘要
硒化铋（Bi₂Se₃）是一种拓扑绝缘体，在热电、自旋电子学和光电子学领域具有潜在应用，但它对辐射的响应机制仍知之甚少。本研究在浦项加速器实验室X射线自由电子激光（PAL-XFEL）装置上，利用同步透射X射线显微镜（TXM）和X射线衍射（XRD）技术，对Bi₂Se₃在27000个连续脉冲下的累积X射线损伤进行研究。研究观测到两种不同的损伤机制：在100个脉冲内通过汽化形成快速孔洞，随后在数千次热循环中发生较慢的晶粒细化和材料溅射。Williamson-Hall分析显示，材料从单晶向纳米晶结构逐步转变，晶粒尺寸从微米级减小至纳米级。有限元模拟证实，X射线的穿透深度为13.47μm，可使局部温度升至1600K以上，且脉冲间存在冷却过程。扫描电子显微镜识别出三种对应不同热历史的特征形貌：溅射条纹、棱柱形晶体和无序微晶体。研究结果表明，晶界形成会产生反馈机制，加速后续脉冲中的损伤。本研究建立了一种可跨多个长度尺度研究辐射损伤的方法，并为理解拓扑绝缘体在极端条件下的稳定性提供了见解。
英文摘要
Bismuth selenide (Bi2Se3) is a topological insulator with potential applications in thermoelectrics, spintronics, and optoelectronics. However, its response to radiation remains poorly understood. We investigate cumulative X-ray damage in Bi2Se3 using simultane- ous transmission X-ray microscopy (TXM) and X-ray diffraction (XRD) at the Pohang Accelerator Laboratory X-Ray Free Electron Laser (PAL-XFEL) over 27,000 successive pulses. We observe distinct damage mechanisms: rapid hole formation via vaporization within 100 pulses, followed by slower grain refinement and material sputtering over thousands of thermal cycles. Williamson-Hall analysis reveals a progressive transformation from single-crystal to nanocrystalline structure, with grain sizes decreasing from mi- cron to nanometer scale. Finite-element modeling confirms that X-rays penetrate 13.47 μm, driving local temperatures above 1600 K with subsequent cooling between pulses. Scanning electron microscopy identifies three characteristic morphologies correspond- ing to different thermal histories: sputter streaks, prismatic crystals, and disordered microcrystals. Our results demonstrate that grain-boundary formation creates a feedback mechanism that accelerates damage in later pulses. This work establishes a method- ology for studying radiation damage across multiple length scales and provides insight into topological insulator stability under extreme conditions
