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Visualizing the Formation of High-Entropy Fluorite Oxides from an Amorphous Precursor at Atomic Resolution
1State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China.
ACS Nano
|December 1, 2022
Summary
This study reveals a four-stage formation mechanism for high-entropy oxides (HEOs) using atomic-resolution microscopy. These insights are crucial for designing advanced HEO materials with tailored properties.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Chemistry
Background:
- High-entropy oxides (HEOs) offer tunable properties for catalysis, energy storage, and thermal barriers.
- Understanding HEO nucleation and growth at the atomic scale is key for material design but remains challenging.
Purpose of the Study:
- To visualize and elucidate the atomic-scale formation mechanism of high-entropy fluorite oxides from a polymeric precursor.
- To provide atomistic insights for the rational synthesis of HEOs with controlled structures and properties.
Main Methods:
- Atomic resolution *in situ* gas-phase scanning transmission electron microscopy (STEM).
- Observation of the entire formation process of HEOs from a polymeric precursor.
Main Results:
- A four-stage formation mechanism was identified: nucleation ( < 400 °C), diffusive grain growth ( < 900 °C), liquid-phase-assisted homogenization (at 900 °C), and entropy-driven recrystallization (>900 °C).
- Visualized the transition from polymeric precursor to stabilized HEO structure.
Conclusions:
- Atomistic insights into HEO formation are critical for controlling grain size and morphology.
- Enables rational synthesis of high-entropy oxides for advanced applications.
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