High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide
Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature applications. Following the concept of high entropy, high-entropy fluorite oxides (HEFOs) have showcased intriguing high-temperature application potential. However, unlocking this potential ne...
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| Format: | Article |
| Language: | English |
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Tsinghua University Press
2024-03-01
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| Series: | Journal of Advanced Ceramics |
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| Online Access: | https://www.sciopen.com/article/10.26599/JAC.2024.9220854 |
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| author | Yixuan Hu Mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy |
| author_facet | Yixuan Hu Mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy |
| author_sort | Yixuan Hu |
| collection | DOAJ |
| description | Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature applications. Following the concept of high entropy, high-entropy fluorite oxides (HEFOs) have showcased intriguing high-temperature application potential. However, unlocking this potential necessitates an assessment of their long-term stability under high-temperature conditions. In this study, we conducted a prolonged heat treatment at 1000 ℃ on typical HEFO, specifically (CeHfZrGdLa)Ox. After 100 h, high-intensity X-ray diffraction (XRD) revealed a transition from a single-phase fluorite to a multi-phase configuration. Further investigation by analytical electron microscoy (AEM) demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures, leading to spontaneous segregation and separation of Ce and La elements, forming Ce-rich, La-poor, and La-rich phases. Notably, the La-rich phase spontaneously transformed from a fluorite structure (space group Fm3¯m) to a bixbyite structure (space group Ia3¯) at elevated temperatures, resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction patterns. Despite the intricate phase decomposition, the energy band gap showed minimal variation, suggesting potential property stability of (CeHfZrGdLa)Ox across a broad range of compositions. These findings offer valuable insights into the future applications of HEFOs. |
| first_indexed | 2024-04-24T08:06:08Z |
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| institution | Directory Open Access Journal |
| issn | 2226-4108 2227-8508 |
| language | English |
| last_indexed | 2024-04-24T08:06:08Z |
| publishDate | 2024-03-01 |
| publisher | Tsinghua University Press |
| record_format | Article |
| series | Journal of Advanced Ceramics |
| spelling | doaj.art-76a31f6f8d1848d6840f1af43e7d7c5d2024-04-17T10:37:39ZengTsinghua University PressJournal of Advanced Ceramics2226-41082227-85082024-03-0113331032210.26599/JAC.2024.9220854High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxideYixuan Hu0Mariappan Anandkumar1Yumeng Zhang2Joydip Joardar3Atul Suresh Deshpande4Xiaodong Wang5Kolan Madhav Reddy6School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaDepartment of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, IndiaSchool of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaInternational Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005, IndiaDepartment of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Sangareddy 502285, IndiaSchool of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaSchool of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaFluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature applications. Following the concept of high entropy, high-entropy fluorite oxides (HEFOs) have showcased intriguing high-temperature application potential. However, unlocking this potential necessitates an assessment of their long-term stability under high-temperature conditions. In this study, we conducted a prolonged heat treatment at 1000 ℃ on typical HEFO, specifically (CeHfZrGdLa)Ox. After 100 h, high-intensity X-ray diffraction (XRD) revealed a transition from a single-phase fluorite to a multi-phase configuration. Further investigation by analytical electron microscoy (AEM) demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures, leading to spontaneous segregation and separation of Ce and La elements, forming Ce-rich, La-poor, and La-rich phases. Notably, the La-rich phase spontaneously transformed from a fluorite structure (space group Fm3¯m) to a bixbyite structure (space group Ia3¯) at elevated temperatures, resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction patterns. Despite the intricate phase decomposition, the energy band gap showed minimal variation, suggesting potential property stability of (CeHfZrGdLa)Ox across a broad range of compositions. These findings offer valuable insights into the future applications of HEFOs.https://www.sciopen.com/article/10.26599/JAC.2024.9220854high-entropy fluorite oxides (hefos)phase transitionhigh-temperature stabilityelemental segregation |
| spellingShingle | Yixuan Hu Mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide Journal of Advanced Ceramics high-entropy fluorite oxides (hefos) phase transition high-temperature stability elemental segregation |
| title | High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide |
| title_full | High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide |
| title_fullStr | High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide |
| title_full_unstemmed | High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide |
| title_short | High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide |
| title_sort | high temperature elemental segregation induced structure degradation in high entropy fluorite oxide |
| topic | high-entropy fluorite oxides (hefos) phase transition high-temperature stability elemental segregation |
| url | https://www.sciopen.com/article/10.26599/JAC.2024.9220854 |
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