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通过在位电子显微镜进行CeO₂的非经典结晶

Hannes Zschiesche¹, Inna L Soroka², Mats Jonsson²

¹Max Planck Institute of Colloids and Interfaces, Department of Colloid Chemistry, Potsdam, Germany. Hannes.Zschiesche@mpikg.mpg.de.

|August 23, 2023

概括

在现场液相电子显微镜 (LP-EM) 粒形成表明,高电子束剂量率与玛辐射相比,不会改变生长路径. 非经典的结晶导致有序的中晶体结构.

科学领域:

材料科学材料科学材料科学
纳米技术纳米技术
物理化学物理化学

背景情况:

在现场液相电子显微镜 (LP-EM) 是一种强大的工具,用于观察纳米级的动态过程.
了解电子束辐射对LP-EM溶液化学和粒子形成的影响对于准确解释结果至关重要.
常常缺乏LP-EM和大量实验之间的比较,这限制了LP-EM结果的验证.

研究的目的:

用Ce3+的放射性氧化作为模型系统研究二氧化 (CeO2) 颗粒的形成.
为了比较LP-EM中高电子束剂量率与玛辐射中较低剂量率对CeO2粒子增长的影响.
分析辐射剂量速率和离子扩散对CeO2粒子生长机制和形态学的影响.

主要方法:

使用现场液相电子显微镜 (LP-EM) 来观察CeO2粒子形成.
采用Ce3+在水溶液中的放射性氧化作为模型反应.
将LP-EM的发现与之前的大量实验进行了比较,这些实验使用Ce3+前体溶液的马辐射.
系统地分析了不同辐射剂量速率和诱导离子扩散对粒子生长和形态学的影响.

主要成果:

尽管LP-EM的剂量比马辐射高八个数量级,但CeO2粒子生长途径没有受到影响.
在LP-EM和玛辐射实验中形成了高度排序的中晶体结构,这表明非经典晶体通过中间阶段形成.
使用LP扫描传输电子显微镜 (LP-STEM) 的局部辐射诱导了Ce-ion度梯度,影响了CeO2的增长.
在LP-STEM下观察到分支的CeO2形态,与转向扩散有限生长相关.

结论:

CeO2颗粒的生长途径是稳固的,并且不会因LP-EM和玛辐射之间的剂量速率差异而显著改变.
非经典的结晶,涉及通过中间阶段逐步形成,是创建有序中晶体结构的关键机制.
在LP-STEM中局部电子束辐射可以引入影响粒子形态的度梯度,导致扩散有限的生长和分支结构.

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