Correlated Terahertz phonon-ion interactions control ion conduction in a solid electrolyte

Kim H. Pham; Kiarash Gordiz; Natan A. Spear; Amy K. Lin; Jonathan M. Michelsen; Hanzhe Liu; Daniele Vivona; Geoffrey A. Blake; Yang Shao-Horn; Asegun Henry; Kimberly A. See; Scott K. Cushing

arXiv · 2305.01632

Correlated Terahertz phonon-ion interactions control ion conduction in a solid electrolyte

Kim H. Pham·Kiarash Gordiz·Natan A. Spear·Amy K. Lin·Jonathan M. Michelsen·Hanzhe Liu·Daniele Vivona·Geoffrey A. Blake·Yang Shao-Horn·Asegun Henry·Kimberly A. See·Scott K. Cushing

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Abstract

Ionic conduction in solids that exceeds 1 mS/cm 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.

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Kim H. Pham, Kiarash Gordiz, Natan A. Spear, Amy K. Lin, Jonathan M. Michelsen, Hanzhe Liu, Daniele Vivona, Geoffrey A. Blake, Yang Shao-Horn, Asegun Henry, Kimberly A. See, Scott K. Cushing. 2023-05-02. Correlated Terahertz phonon-ion interactions control ion conduction in a solid electrolyte. https://arxiv.org/abs/2305.01632

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