Visualizing the Formation of High-Entropy Fluorite Oxides from an Amorphous Precursor at Atomic Resolution

Lei Su; Xi Chen; Liang Xu; Tim Eldred; Jacob Smith; Cierra Dellarova; Hongjie Wang; Wenpei Gao

doi:10.1021/acsnano.2c09760

Visualizing the Formation of High-Entropy Fluorite Oxides from an Amorphous Precursor at Atomic Resolution

Lei Su, Xi Chen, Liang Xu, Tim Eldred, Jacob Smith, Cierra Dellarova, Hongjie Wang, Wenpei Gao

electron Microscopy and Microanalysis

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

High-entropy oxides (HEOs) have a large tuning space in composition and crystal structures, offering the possibility for improved material properties in applications including catalysis, energy storage, and thermal barrier coatings. Understanding the nucleation and growth mechanisms of HEOs at the atomic scale is critical to the design of their structure and functions but remains challenging. Herein, we visualize the entire formation process of a high-entropy fluorite oxide from a polymeric precursor using atomic resolution in situ gas-phase scanning transmission electron microscopy. The results show a four-stage formation mechanism, including nucleation during the oxidation of a polymeric precursor below 400 °C, diffusive grain growth below 900 °C, liquid-phase-assisted compositional homogenization under a "state of supercooling" at 900 °C, and entropy-driven recrystallization and stabilization at higher temperatures. The atomistic insights are critical for the rational synthesis of HEOs with controlled grain sizes and morphologies and thus the related properties.

Original language	English
Pages (from-to)	21397-21406
Number of pages	10
Journal	ACS Nano
Volume	16
Issue number	12
DOIs	https://doi.org/10.1021/acsnano.2c09760
State	Published - Dec 27 2022

Funding

X.C., T.E., C.D., J.S., and W.G. are supported by the College of Engineering at North Carolina State University. L.S., L.X., and H.W. are supported by the National Natural Science Foundation of China (52072294, 52102076, 51772237). L.S. also acknowledges the support from the China Postdoctoral Science Foundation (2021M690122). T.E. is partially supported by the National Science Foundation under Grant No. DGE 1633587. Electron microscopy was performed at the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (Award No. ECCS-2025064). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI).

Keywords

amorphous precursor
grain growth
high-entropy oxide
liquid phase
nucleation

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10.1021/acsnano.2c09760

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abstract = "High-entropy oxides (HEOs) have a large tuning space in composition and crystal structures, offering the possibility for improved material properties in applications including catalysis, energy storage, and thermal barrier coatings. Understanding the nucleation and growth mechanisms of HEOs at the atomic scale is critical to the design of their structure and functions but remains challenging. Herein, we visualize the entire formation process of a high-entropy fluorite oxide from a polymeric precursor using atomic resolution in situ gas-phase scanning transmission electron microscopy. The results show a four-stage formation mechanism, including nucleation during the oxidation of a polymeric precursor below 400 °C, diffusive grain growth below 900 °C, liquid-phase-assisted compositional homogenization under a {"}state of supercooling{"} at 900 °C, and entropy-driven recrystallization and stabilization at higher temperatures. The atomistic insights are critical for the rational synthesis of HEOs with controlled grain sizes and morphologies and thus the related properties.",

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AU - Chen, Xi

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AU - Eldred, Tim

AU - Smith, Jacob

AU - Dellarova, Cierra

AU - Wang, Hongjie

AU - Gao, Wenpei

PY - 2022/12/27

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Visualizing the Formation of High-Entropy Fluorite Oxides from an Amorphous Precursor at Atomic Resolution

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Keywords

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