Issue 5, 2022

Anharmonic lattice dynamics of superionic lithium nitride

Abstract

Superionic crystals reach an ionic conductivity comparable to liquid electrolytes following a superionic transition at high temperature. The physical mechanisms that lead to this behaviour remain poorly understood. It has been proposed that superionic transitions are accompanied by the breakdown of specific phonon modes linked to characteristic diffusion processes. Any changes in vibrational properties across the superionic transition may therefore provide insights into the underlying physics of this phenomenon. Here, we apply a combination of lattice dynamics and ab initio molecular dynamics to probe the vibrational properties of the archetypal superionic conductor Li3N. We assess harmonic, quasi-harmonic, and anharmonic descriptions of the phonons. The harmonic and quasi-harmonic models show no change in features across the superionic transition. The anharmonic model, however, exhibits a breakdown for all modes. The implications for developing lattice-dynamics-based descriptors for superionic conductors are discussed.

Graphical abstract: Anharmonic lattice dynamics of superionic lithium nitride

Supplementary files

Article information

Article type
Paper
Submitted
05 Sep 2021
Accepted
19 Okt 2021
First published
19 Okt 2021
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2022,10, 2295-2304

Anharmonic lattice dynamics of superionic lithium nitride

G. Krenzer, C. Kim, K. Tolborg, B. J. Morgan and A. Walsh, J. Mater. Chem. A, 2022, 10, 2295 DOI: 10.1039/D1TA07631K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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