A Comparison of a Direct Electron Detector and a High-Speed Video Camera for a Scanning Precession Electron Diffraction Phase and Orientation Mapping.
A Comparison of a Direct Electron Detector and a High-Speed Video Camera for a Scanning Precession Electron Diffraction Phase and Orientation Mapping.
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用于扫描进动电子衍射相位和方向映射的直接电子探测器和高速摄像机的比较。
DOI：
10.1017/s1431927620024411
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
MacLaren I
中科院分区：
文献类型：
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作者：
MacLaren I
扫描进动电子衍射系统已与直接电子检测器集成，以允许收集质量改进的衍射图案。这已被用于两相α-β钛合金（Timetal® 575），使用现有的模式匹配算法进行相位和取向映射，并与常用的检测器系统进行了比较，后者由高速摄像机成像的小荧光聚焦屏幕组成。直接电子检测器的噪声明显较低，并且这在远离衍射图案中心处尤其明显，在衍射图案中心处，真实的电子散射减少，并且衍射斑点和斑点之间的非弹性散射都较弱。取向映射的结果是相位和取向索引可靠性的显著改善，特别是α-Ti的精细纳米级板条，其中弱衍射信号相当丢失在光耦合相机的噪声中。这是在~19 e−/μ 2的剂量下完成的，并且很明显有进一步降低电流同时仍然产生可转位图案的前景。这为辐射敏感晶体材料的旋进衍射相位和取向映射开辟了道路。
A scanning precession electron diffraction system has been integrated with a direct electron detector to allow the collection of improved quality diffraction patterns. This has been used on a two-phase α–β titanium alloy (Timetal® 575) for phase and orientation mapping using an existing pattern-matching algorithm and has been compared to the commonly used detector system, which consisted of a high-speed video-camera imaging the small phosphor focusing screen. Noise is appreciably lower with the direct electron detector, and this is especially noticeable further from the diffraction pattern center where the real electron scattering is reduced and both diffraction spots and inelastic scattering between spots are weaker. The results for orientation mapping are a significant improvement in phase and orientation indexing reliability, especially of fine nanoscale laths of α-Ti, where the weak diffracted signal is rather lost in the noise for the optically coupled camera. This was done at a dose of ~19 e−/Å2, and there is clearly a prospect for reducing the current further while still producing indexable patterns. This opens the way for precession diffraction phase and orientation mapping of radiation-sensitive crystalline materials.