| About this Abstract |
| Meeting |
2023 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advances in Multi-Principal Element Alloys II
|
| Presentation Title |
J-8: Abrupt Fluorite-pyrochlore and Pyrochlore-weberite Phase Transformations in Single-phase 20-component Ultrahigh-entropy Oxides |
| Author(s) |
Keqi Song, Dawei Zhang, Jian Luo |
| On-Site Speaker (Planned) |
Keqi Song |
| Abstract Scope |
A new series of 20-component fluorite-based compositionally complex oxides (20CCFBOs) were synthesized. This series of 20CCFBOs undergo a fluorite-pyrochlore transition and a pyrochlore-weberite transition with one varying compositional variable x. Surprisingly, while the Gibbs phase rule allows the co-existence of up to 20 phases at thermodynamic equilibrium, 15 out of the 17 compositions possess single ultrahigh-entropy phases, the remaining 2 exhibit minor phases near the transition points. This observation may be explained by a high-entropy effect (prone to stabilize a single solid solution phase). Careful characterization suggests small, but abrupt, changes of order parameters (represented by the XRD superstructure peak intensity or peak splitting due to the change of symmetries) at both phase transformations and the possible existence of short-range order after the vanishing of long-range order. Understanding and controlling such phase transformations suggests a new route to manipulating ordering and properties of high-entropy and compositionally complex ceramics. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Ceramics, Phase Transformations, |