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Computational discovery of fast interstitial oxygen conductors

Abstract

New highly oxygen-active materials may enhance many energy-related technologies by enabling efficient oxygen-ion transport at lower temperatures, for example, below ~400 °C. Interstitial oxygen conductors have the potential to realize such performance but have received far less attention than vacancy-mediated conductors. Here we combine physically motivated structure and property descriptors, ab initio simulations and experiments to demonstrate an approach to discover new fast interstitial oxygen conductors. Multiple new families were found, which adopt completely different structures from known oxygen conductors. From these families, we synthesized and studied oxygen kinetics in La4Mn5Si4O22+δ, a representative member of the perrierite/chevkinite family. We found that La4Mn5Si4O22+δ has higher oxygen-ion conductivity than the widely used yttria-stabilized ZrO2, and among the highest surface oxygen exchange rates at the intermediate temperature of known materials. The fast oxygen kinetics is the result of simultaneously active interstitial and interstitialcy diffusion pathways. We propose that the essential features for forming an effective interstitial oxygen conductor are the availability of electrons and structural flexibility, enabling a sufficient accessible volume. This work provides a powerful approach for understanding and discovering new interstitial oxygen conductors.

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Fig. 1: Oxygen migration barriers in interstitial and vacancy conductors.
Fig. 2: Schematic of the screening approach.
Fig. 3: Bulk structure of fast interstitial oxygen conductors.
Fig. 4: Structure and interstitial oxygen mobility in La4Mn5Si4O22.

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Source data and data that support the plots within this paper are available via figshare at https://doi.org/10.6084/m9.figshare.23808606 (ref. 78). Please refer to the readme.txt file in the repository for guidance. Source data are provided with this paper.

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Acknowledgements

This work was funded by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award no. DE-SC0020419 (J.M., M.S.S., R.J. and D.M.). This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation grant no. ACI-1548562 (to J.M., R.J. and D.M.). This work used the computational resources provided by the Center for High Throughput Computing at the University of Wisconsin–Madison. This work used facilities and instrumentation supported by the National Science Foundation (NSF) through the University of Wisconsin Materials Research Science and Engineering Center (DMR-1720415).

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Contributions

R.J. and D.M. conceived and managed the project. J.M. performed the screening, ab initio calculations and theoretical analyses, with assistance from D.M. and R.J. M.S.S. performed the synthesis, characterization and conductivity and kinetic measurements. J.L. helped with the ECR analysis and contributed to scientific discussions. W.O.N. performed the EPMA analysis. X.L. trained the ML-IP. J.M. wrote the first version of the manuscript with input from M.S.S. R.J. and D.M. reviewed the manuscript. All authors have reviewed and commented on the manuscript.

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Correspondence to Dane Morgan.

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Supplementary information

Supplementary Information

Supplementary Tables 1–6, Figs. 1–16 and Discussions 1–11.

Supplementary Video 1

AIMD simulation showcasing the real-time simultaneous occurrence of interstitial and interstitialcy diffusion mechanisms of oxygen-ion diffusion in La4Mn5Si4O22. The La, Mn and Si sites are shown as light blue, purple and dark blue spheres, respectively. In this video, the interstitial oxygen (red ball) initially hops through the interstitial mechanism to a new interstitial site, and subsequently, it kicks a lattice oxygen (yellow ball) to another interstitial site, which then, in turn, kicks another lattice oxygen (orange ball) to another interstitial site. This latter step represents an interstitialcy mechanism. The simulation was conducted at 2,000 K using the SCAN functional.

Supplementary Video 2

AIMD simulation showcasing the interstitial-oxygen-ion diffusion in K2Mn2(MoO4)3. The K, Mn, Mo and O sites are shown as big purple, small purple, grey and red spheres, respectively. In this video, the interstitial oxygen (yellow ball) kicks out the lattice oxygen (orange ball) to another interstitial site along with the facile polyhedra rotation. The simulation was conducted at 1,600 K using the GGA-PBE functional.

Supplementary Video 3

AIMD simulation showcasing the interstitial-oxygen-ion diffusion in CeMn2Ge4O12. The Ce, Mn, Ge and O sites are shown as green, purple, blue and red spheres, respectively. In this video, the interstitial oxygen (yellow ball) in between two corner-sharing Ge tetrahedra kicks a lattice oxygen (black ball) to the Ce tunnel, which then kicks another lattice oxygen (blue ball) to the interstitial site in between two Ge tetrahedra. The interstitial oxygen diffuses through an interstitialcy mechanism in CeMn2Ge4O12. The simulation was conducted at 2,000 K using the GGA-PBE functional.

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Meng, J., Sheikh, M.S., Jacobs, R. et al. Computational discovery of fast interstitial oxygen conductors. Nat. Mater. (2024). https://doi.org/10.1038/s41563-024-01919-8

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