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DOE OSTI · 2587806

Selective Oxidation and Cr Segregation in High-Entropy Oxide Thin Films

Wang, Le [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000277309482)·Koirala, Krishna Prasad [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Wu, Shuhang [Queensland University of Technology, Brisbane, QLD (Australia)]·Shi, Jueli [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Kao, Hsin-Mei [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Oregon State University, Corvallis, OR (United States)] (ORCID:0009000034186315)·Ho, Andrew [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Santa Rosa Junior College, CA (United States)]·Choi, Min-Ju [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Mantilla, Alexander B. C. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Qi, Dongchen [Queensland University of Technology, Brisbane, QLD (Australia)] (ORCID:0000000184660257)·Tadich, Anton [Australian Nuclear Science and Technology Organisation (ANSTO), Melbourne, VIC (Australia). Australian Synchrotron] (ORCID:0000000194555901)·Bowden, Mark E. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000338123340)·Matthews, Bethany E. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000171932583)·Zhou, Hua [Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)] (ORCID:0000000196428674)·Yang, Yang [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000153185385)·Chang, Chih-hung [Oregon State University, Corvallis, OR (United States)] (ORCID:0000000334293940)·Zhu, Zihua [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000157708462)·Wang, Chongmin [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000333270958)·Du, Yingge [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000196801950)
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Abstract

High-entropy oxides (HEOs) offer exceptional compositional flexibility and structural stability, making them promising materials for energy and catalytic applications. Here, in this study, we investigate Sr doping effects on B-site cation oxidation states, local composition, and structure in epitaxial La 1–x Sr x (Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 thin films. X-ray spectroscopies reveal that Sr doping preferentially promotes Cr oxidation from Cr 3+ to Cr 6+ , partially oxidizes Co and Ni, while leaving Mn 4+ and Fe 3+ unchanged. Atomic-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy shows pronounced Cr segregation, with depletion at the interface and enrichment at the surface, along with partial amorphization in heavily Sr-doped samples. This segregation is likely driven by oxidation-induced migration of smaller, high-valence Cr cations during growth. These findings highlight the critical interplay between charge compensation, local strain, and compositional fluctuations in HEOs, indicating that precise control over growth conditions is critical for tuning their surface composition and electronic structure toward more robust electrocatalyst design.

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36 MATERIALS SCIENCEcation migrationdopingepitaxial thin filmshigh entropy oxidesselective oxidation

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Wang, Le [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000277309482), Koirala, Krishna Prasad [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Wu, Shuhang [Queensland University of Technology, Brisbane, QLD (Australia)], Shi, Jueli [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Kao, Hsin-Mei [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Oregon State University, Corvallis, OR (United States)] (ORCID:0009000034186315), Ho, Andrew [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Santa Rosa Junior College, CA (United States)], Choi, Min-Ju [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Mantilla, Alexander B. C. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Qi, Dongchen [Queensland University of Technology, Brisbane, QLD (Australia)] (ORCID:0000000184660257), Tadich, Anton [Australian Nuclear Science and Technology Organisation (ANSTO), Melbourne, VIC (Australia). Australian Synchrotron] (ORCID:0000000194555901), Bowden, Mark E. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000338123340), Matthews, Bethany E. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000171932583), Zhou, Hua [Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)] (ORCID:0000000196428674), Yang, Yang [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000153185385), Chang, Chih-hung [Oregon State University, Corvallis, OR (United States)] (ORCID:0000000334293940), Zhu, Zihua [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000157708462), Wang, Chongmin [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000333270958), Du, Yingge [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000196801950). 2025-08-11. Selective Oxidation and Cr Segregation in High-Entropy Oxide Thin Films. https://doi.org/10.1021/acs.nanolett.5c03196

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36 MATERIALS SCIENCE↗