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| Autori principali: | , , , , , , , , , , , , , , , , |
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| Natura: | Preprint |
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2025
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| Accesso online: | https://arxiv.org/abs/2503.17470 |
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| _version_ | 1866915209153609728 |
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| author | Wang, Le Koirala, Krishna Prasad Wu, Shuhang Shi, Jueli Kao, Hsin-Mei Ho, Andrew Choi, Min-Ju Qi, Dongchen Tadich, Anton Bowden, Mark E. Matthews, Bethany E. Zhou, Hua Yang, Yang Chang, Chih-hung Zhu, Zihua Wang, Chongmin Du, Yingge |
| author_facet | Wang, Le Koirala, Krishna Prasad Wu, Shuhang Shi, Jueli Kao, Hsin-Mei Ho, Andrew Choi, Min-Ju Qi, Dongchen Tadich, Anton Bowden, Mark E. Matthews, Bethany E. Zhou, Hua Yang, Yang Chang, Chih-hung Zhu, Zihua Wang, Chongmin Du, Yingge |
| contents | High-entropy oxides (HEOs) offer exceptional compositional flexibility and structural stability, making them promising materials for energy and catalytic applications. Here, we investigate Sr doping effects on B-site cation oxidation states, local composition, and structure in epitaxial La1-xSrx(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 thin films. X-ray spectroscopies reveal that Sr doping preferentially promotes Cr oxidation from Cr3+ to Cr6+, partially oxidizes Co and Ni, while leaving Mn4+ and Fe3+ unchanged. Atomic-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy shows pronounced Cr segregation, with Cr exhibiting depletion at the film-substrate interface and enrichment at the film surface, along with the formation of a partially amorphous phase in heavily Sr-doped samples. This segregation is likely driven by oxidation-induced migration of smaller, high-valence Cr cations during the growth. These findings underscore the critical interplay between charge transfer, local strain, and compositional fluctuations, providing strategies to control surface composition and electronic structure in HEOs for more robust electrocatalyst design. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_17470 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Selective Oxidation and Cr Segregation in High-Entropy Oxide Thin Films Wang, Le Koirala, Krishna Prasad Wu, Shuhang Shi, Jueli Kao, Hsin-Mei Ho, Andrew Choi, Min-Ju Qi, Dongchen Tadich, Anton Bowden, Mark E. Matthews, Bethany E. Zhou, Hua Yang, Yang Chang, Chih-hung Zhu, Zihua Wang, Chongmin Du, Yingge Materials Science High-entropy oxides (HEOs) offer exceptional compositional flexibility and structural stability, making them promising materials for energy and catalytic applications. Here, we investigate Sr doping effects on B-site cation oxidation states, local composition, and structure in epitaxial La1-xSrx(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 thin films. X-ray spectroscopies reveal that Sr doping preferentially promotes Cr oxidation from Cr3+ to Cr6+, partially oxidizes Co and Ni, while leaving Mn4+ and Fe3+ unchanged. Atomic-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy shows pronounced Cr segregation, with Cr exhibiting depletion at the film-substrate interface and enrichment at the film surface, along with the formation of a partially amorphous phase in heavily Sr-doped samples. This segregation is likely driven by oxidation-induced migration of smaller, high-valence Cr cations during the growth. These findings underscore the critical interplay between charge transfer, local strain, and compositional fluctuations, providing strategies to control surface composition and electronic structure in HEOs for more robust electrocatalyst design. |
| title | Selective Oxidation and Cr Segregation in High-Entropy Oxide Thin Films |
| topic | Materials Science |
| url | https://arxiv.org/abs/2503.17470 |