Direct observation of oxygen vacancy ordering evolution in cerium oxide at varying concentrations via high-resolution transmission electron microscopy

IF 2.1 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy Pub Date : 2025-03-15 DOI:10.1016/j.ultramic.2025.114133

Yong Ding , Yuzi Liu , Yu Chen , Meilin Liu , Zhong Lin Wang

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引用次数: 0

Abstract

Under illumination by a 300 keV electron beam, oxygen vacancy ordering structures are induced within cerium oxide grains. Our high-resolution transmission electron microscopy (HRTEM) study, supported by image simulation, reveals the evolution of these structures as vacancy concentration increases. The observed fluorite-type superlattice structures are identified as CeO_1.825, CeO_1.75, Ce₂O₃, displaying a gradient in oxygen vacancy concentration moving away from the grain surface. Correspondingly, the structural sequence transitions from Ce₂O₃ to CeO_1.75 and then to CeO_1.825. Without the constraints of surrounding grains, fluorite-type Ce₂O₃ nanocrystals show a preference for transformation into an A-type trigonal structure. Notably, at temperatures up to 200°C, only the perfect fluorite structure is observed. Structural models were validated through both [110] and [001] projections. Our findings further confirm lattice expansion associated with local oxygen vacancy enrichment, which can be compensated by the formation of stacking faults, where a {111} oxygen plane is lost at defect sites.

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用高分辨率透射电镜直接观察不同浓度氧化铈中氧空位有序演化

在300 keV的电子束照射下，氧化铈颗粒内诱导出氧空位有序结构。我们的高分辨率透射电子显微镜（HRTEM）研究，在图像模拟的支持下，揭示了这些结构随着空位浓度的增加而演变。观察到的萤石型超晶格结构分别为CeO1.825、CeO1.75、Ce2O3，氧空位浓度呈梯度远离晶粒表面。相应的，结构顺序从Ce2O3到CeO1.75再到CeO1.825。在没有周围晶粒约束的情况下，萤石型Ce2O3纳米晶倾向于转变为a型三角形结构。值得注意的是，在高达200°C的温度下，只观察到完美的萤石结构。结构模型通过[110]和[001]投影验证。我们的研究结果进一步证实了晶格膨胀与局部氧空位富集有关，这可以通过层错的形成来补偿，在缺陷处丢失了一个{111}氧面。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Ultramicroscopy 工程技术-显微镜技术

CiteScore

4.60

自引率

13.60%

发文量

117

审稿时长

5.3 months

期刊介绍： Ultramicroscopy is an established journal that provides a forum for the publication of original research papers, invited reviews and rapid communications. The scope of Ultramicroscopy is to describe advances in instrumentation, methods and theory related to all modes of microscopical imaging, diffraction and spectroscopy in the life and physical sciences.