In situ X-ray scattering of epitaxial oxide thin films

Zhou, Hua; Fong, Dillon D.

doi:10.1016/b978-0-08-102945-9.00017-4

Cited by 1 publication

(3 citation statements)

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“…Many of the material descriptors in fields of electrochemical devices were developed on the basis of the bulk structure of the oxides, ,, although it is acknowledged that catalytic and electrochemical performances are determined by phenomena at the surface/interface. ,, This reveals an inherent discrepancy because the bulk and the surface can differ in chemical composition as well as in the crystalline and electronic structures. , Of the many techniques available, SXRD is a particularly powerful approach for studying the surface and interface structure in epitaxial films. A smooth epitaxial surface leads to the formation of crystal truncation rods (CTRs) in reciprocal space (Figure c) . These rods appear at every Bragg reflection and extend along the surface normal direction, as displayed in reciprocal space.…”

Section: X-ray Probes For Monitoring Structural and Chemical Transfor...mentioning

confidence: 95%

“…A smooth epitaxial surface leads to the formation of crystal truncation rods (CTRs) in reciprocal space (Figure 2c). 15 These rods appear at every Bragg reflection and extend along the surface normal direction, as displayed in reciprocal space. In Figure 2c, we depict the Ewald sphere construction in which scattering takes place at an "anti-Bragg" position, i.e., the midzone between Bragg reflections.…”

Section: X-ray Probes For Monitoring Structural and Chemical Transfor...mentioning

confidence: 99%

“…(c) Geometries for surface X-ray diffraction (SXRD), where the incoming and outgoing vectors for X-rays are labeled k i and k f , respectively. Reproduced with permission from ref . Copyright 2015 Elsevier.…”

Section: X-ray Probes For Monitoring Structural and Chemical Transfor...mentioning

confidence: 99%

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Defect-Driven Oxide Transformations and the Electrochemical Interphase

et al. 2021

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Conspectus The redox reaction pathway is crucial to the sustainable production of the fuels and chemicals required for a carbon-neutral society. Our society is becoming increasingly dependent on devices using batteries and electrolyzers, all of which rely on a series of redox reactions. The overall properties of oxide materials make them very well suited for such electrochemical and catalytic applications due to their associated cationic redox properties and the static site–adsorbate interactions. As these technologies have matured, it has become apparent that defect-driven redox reactions, defect-coupled diffusion, and structural transformations that are both time- and rate-dependent are also critical materials processes. This change in focus, considering not only redox properties but also more complex, dynamic behaviors, represents a new research frontier in the molecular sciences as they are strongly linked to device operation and degradation and lie at the heart of various phenomena that take place at electrochemical interfaces. Fundamental studies of the structural, electronic, and chemical transformation mechanisms are key to the advancement of materials and technological innovations that could be implemented in various electrochemical systems. In this Account, we focus on recent studies and advances in characterizing and understanding the dynamic redox evolution and structural transformations that take place in model perovskites and layered oxides under reactive conditions and correlate them with degradation mechanisms and operations in electrolyzers and batteries. We show that the dynamic evolution of oxygen vacancies and cationic migration in the surface or bulk occurs at the solid–liquid interface, using a combination of different synchrotron-based X-ray spectroscopies and scattering probes. Detailed redox–structure–reactivity correlation studies show how defects and diffusion processes can be tailored to drive various physical and chemical transformations in electrolyzers and batteries. We also highlight a strong correlation between oxygen redox reactivity and structural reorganization in both model thin films and particles, helping to bridge the gap between fundamental studies of the reaction mechanism and device applications. On the basis of these findings, we discuss strategies to probe and tune the redox reactivity and structural stability of the redox-active oxide interphase toward devising efficient pathways for energy and chemical harvesting.

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