Bulk and Short-Circuit Anion Diffusion in Epitaxial Fe2O3 Films Quantified Using Buried Isotopic Tracer Layers

Tiffany C. Kaspar, Sandra D. Taylor, Kayla H. Yano, Timothy G. Lach, Yadong Zhou, Zihua Zhu, Aaron A. Kohnert, Evan K. Still, Peter Hosemann, Steven R. Spurgeon, Daniel K. Schreiber

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Self-diffusion is a fundamental physical process that, in solid materials, is intimately correlated with both microstructure and functional properties. Local transport behavior is critical to the performance of functional ionic materials for energy generation and storage, and drives fundamental oxidation, corrosion, and segregation phenomena in materials science, geosciences, and nuclear science. Here, an adaptable approach is presented to precisely characterize self-diffusion in solids by isotopically enriching component elements at specific locations within an epitaxial film stack, and measuring their redistribution at high spatial resolution in 3D with atom probe tomography. Nanoscale anion diffusivity is quantified in a-Fe2O3 thin films deposited by molecular beam epitaxy with a thin (10 nm) buried tracer layer highly enriched in 18O. The isotopic sensitivity of the atom probe allows precise measurement of the initial sharp layer interfaces and subsequent redistribution of 18O after annealing. Short-circuit anion diffusion through 1D and 2D structural defects in Fe2O3 is also directly visualized in 3D. This versatile approach to study precisely tailored thin film samples at high spatial and mass fidelity will facilitate a deeper understanding of atomic-scale diffusion phenomena.

Original languageEnglish
Article number2001768
JournalAdvanced Materials Interfaces
Volume8
Issue number9
DOIs
StatePublished - May 7 2021

Funding

This work was supported as part of FUTURE (Fundamental Understanding of Transport Under Reactor Extremes), an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. The authors acknowledge fruitful discussions with Drs. Dan Edwards, Matthew Olszta, and T.S. Byun. The authors graciously acknowledge the assistance of Drs. Ty Prosa and Yimeng Chen at CAMECA Instruments (Madison, WI) for the data collected on the LEAP 5000XR. A portion of the research was performed using EMSL (grid.436923.9), a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program and located at Pacific Northwest National Laboratory. Additional STEM imaging was performed in the Radiological Microscopy Suite (RMS), located in the Radiochemical Processing Laboratory (RPL) at PNNL. Pacific Northwest National Laboratory is a multi-program national laboratory operated by Battelle for the U.S. DOE under Contract DE-AC05-79RL01830. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is managed by Triad National Security, LLC for the U.S. Department of Energy's NNSA, under contract 89233218CNA000001.

Keywords

  • anion diffusion
  • atom probe tomography
  • isotopic tracers
  • low-angle grain boundary

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