Correlated terahertz phonon–ion interactions control ion conduction in a solid electrolyte
Creators
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1.
California Institute of Technology
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2.
Massachusetts Institute of Technology
Abstract
Ionic conduction in solids that exceeds 1 mS cm−1 is predicted to involve coupled phonon–ion interactions in the crystal lattice. Here, we use theory and experiment to measure the possible contribution of coupled phonon–ion hopping modes which enhance Li+ migration in Li0.5La0.5TiO3 (LLTO). The ab initio calculations predict that the targeted excitation of individual TiO6 rocking modes greatly increases the Li+ jump rate as compared to the excitation of vibrational modes associated with heating. Experimentally, coherently driving TiO6 rocking modes via terahertz (THz) illumination leads to a ten-fold decrease in the differential impedance compared to the excitation of acoustic and optical phonons. Additionally, we differentiate the ultrafast responses of LLTO due to ultrafast heating and THz-range vibrations using laser-driven spectroscopy (LUIS), finding a unique long-lived response for the THz-range excitation. These findings provide new insights into coupled ion migration mechanisms, indicating the important role of THz-range coupled phonon–ion hopping modes in enabling fast ion conduction at room temperature.
Copyright and License
© The Royal Society of Chemistry 2026. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.
Acknowledgement
KHP acknowledges financial support from the National Science Foundation, Air Force Office of Science & Research under award number FA9550-21-1-0022, and David & Lucile Packard Foundation. AKL acknowledges support by the California Institute of Technology through the Beckman-Gray Graduate Fellowship and the Natural Sciences and Engineering Research Council of Canada, funding reference number 599279. NAS acknowledges financial support by the National Defense Science and Engineering Graduate Fellowship. NAS and AKL acknowledge additional personnel support from the U.S. Army Research Office (ARO), grant number W911NF-23-1-0001. We also acknowledge support for the equipment used in this work by the Air Force Office of Science Research (AFOSR), DURIP grant number FA9550-23-1-0197. FT-IR data was collected at the Laser Resource Center in the Beckman Institute of the California Institute of Technology with the assistance of Dr Jay Winkler. Solid-state UV-VIS data was collected at the Earle M. Jorgenson Laboratory of the California Institute of Technology with the assistance of Dr Weilai Yu. We thank Prof. David Hsieh and Dr Omar Mehio for assistance in using the difference frequency generation unit for IR light. We thank Ricardo Zarazua at the Chemistry and Chemical Engineering Machine Shop for machining the custom heating cell in this work. We thank Dr Zachery W. B. Iton for assistance with the characterization of LLTO. We thank Jadon Bienz for assistance with analysis of the XRD data including multi-phase Rietveld refinements of LLTO. We thank Jax Dallas for generating the THz light for the THz absorption and ultrafast impedance measurements. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH1135. The finite-difference time-domain heating model computations were conducted in the Resnick High Performance Computing Center at the Resnick Sustainability Institute at the California Institute of Technology.
Data Availability
The data supporting this article have been included as part of the supplementary information (SI). Supplementary information is available. The SI containts details on the X-ray diffraction, DFT and MD simulations, laser-driven EIS experiments, THz light generation, the LUIS experiments, and the FDTD heating model. See DOI: https://doi.org/10.1039/d5mh01990g.
Code Availability
The code is available under the MIT license and can be found at https://github.com/kgordiz/modalNEB.
Supplemental Material
Files
d5mh01990g.pdf
Additional details
Additional titles
- Alternative title
- Many-body phonon-ion conduction in solid electrolyte driven by THz modes
- Alternative title
- Correlated Terahertz phonon-ion interactions dominate ion conduction in solid electrolyte Li0.5La0.5TiO3
Identifiers
- PMID
- 41603889
Related works
- Is new version of
- Discussion Paper: arXiv:2305.01632 (arXiv)
Funding
- National Science Foundation
- United States Air Force Office of Scientific Research
- FA9550-21-1-0022
- David and Lucile Packard Foundation
- California Institute of Technology
- Beckman-Gray Graduate Fellowship -
- Natural Sciences and Engineering Research Council
- 599279
- United States Department of Defense
- United States Army Research Office
- W911NF-23-1-0001
- United States Air Force Office of Scientific Research
- FA9550-23-1-0197
- United States Department of Energy
- DE-AC02-06CH1135
Dates
- Submitted
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2025-10-21
- Accepted
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2026-01-16
- Available
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2026-01-16First published
Caltech Custom Metadata
- Caltech groups
- Division of Geological and Planetary Sciences (GPS) , Division of Chemistry and Chemical Engineering (CCE) , Division of Engineering and Applied Science (EAS)
- Publication Status
- Published