Unveiling the Oxidation Mechanisms of High-entropy Carbides Through Atomic-scale Dynamic Observation
© 2025 Wiley‐VCH GmbH.
| Veröffentlicht in: | Advanced materials (Deerfield Beach, Fla.). - 1998. - (2025) vom: 02. Jan., Seite e2417846 |
|---|---|
| 1. Verfasser: | |
| Weitere Verfasser: | , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2025
|
| Zugriff auf das übergeordnete Werk: | Advanced materials (Deerfield Beach, Fla.) |
| Schlagworte: | Journal Article High‐entropy carbides atomic‐scale structural evolution in situ measurements oxidation mechanisms |
| Zusammenfassung: | © 2025 Wiley‐VCH GmbH. Understanding the behavior of high-entropy carbides (HECs) under oxygen-containing environments is of particular importance for their promising applications in structural components, catalysis, and energy-related fields. Herein, the structural evolution of (Ta, Ti, Cr, Nb)C (HEC-1) nanoparticles (NPs) is tracked in situ during the oxidation at the atomic scale by using an open-cell environmental aberration-corrected scanning transmission electron microscope. Three key stages are clearly discerned during the oxidation of HEC-1 NPs at the atomic level below 900 °C: i) increased amorphization of HEC-1 NPs from 300 to 500 °C due to the energetically favorable formation of carbon vacancies and substitution of carbon with oxygen atoms; ii) nucleation and subsequent growth of locally ordered nanocluster intermediates within the generated amorphous oxides from 500 to 800 °C; and iii) final one-step crystallization of non-equimolar MeO2 and Me2O5 (Me = metallic elements, Ta, Ti, Cr, and Nb) high-entropy oxides above 800 °C, accompanied with the reduction in atomic defects. This result is further confirmed by theoretical calculations that these observed high-entropy oxide phases are thermodynamically preferable to generate above 830 °C. The study provides direct evidence of the ordered-disordered-ordered structural transition of HECs during oxidation |
|---|---|
| Beschreibung: | Date Revised 02.01.2025 published: Print-Electronic Citation Status Publisher |
| ISSN: | 1521-4095 |
| DOI: | 10.1002/adma.202417846 |