Fast Na diffusion and anharmonic phonon dynamics in superionic Na<sub>3</sub>PS<sub>4</sub>

Gupta, Mayanak K.; Ding, Jingjin; Osti, Naresh C.; Abernathy, D. L.; Arnold, William A.; Wang, Hui; Hood, Zachary D.; Delaire, Olivier

doi:10.1039/d1ee01509e

Cited by 44 publications

(78 citation statements)

References 55 publications

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“…In this study, we investigate the temperaturedependent lattice dynamics of the foundational sodium ion conductors Na 3 PS 4 and Na 3 PSe 4 through THz-range Raman scattering and first-principles calculations. In both compounds, we clearly identify anharmonic vibrational modes involving coupled host lattice-Na + ion motion that drive the tetragonal-to-cubic (t-c) phase transition, as reported previously in Na 3 PS 4 7,29 . Moreover, we demonstrate regime-crossing tunability of the material's anharmonic character through the conceptually simple homovalent substitution of S for Se: while the phase transition is displacive in Na 3 PSe 4 , Na 3 PS 4 exhibits dynamic symmetry breaking in a phase that is cubic only on average.…”

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confidence: 80%

“…The development of new, stable, and highly conductive SSICs requires a clear understanding of which material properties are essential to ion conductivity. Intensive research in recent years indicates that many highly conductive SSIC materials exhibit lattice dynamical phenomena consistent with strong anharmonicity [2][3][4][5][6][7][8][9][10][11][12] . Anharmonicity refers to the coupling that occurs between vibrational normal modes (or, phonons) of the lattice 13,14 .…”

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confidence: 99%

“…In a recent important study, Gupta et al used neutron scattering and molecular dynamics (MD) to establish the connection between anharmonic phonon dynamics and superionic conductivity in Na 3 PS 4 7 . This material is a parent compound of Na 3−x P 1−x W x S 4 , a record Na + con-ductivity compound in which Na + vacancies have been introduced through tungsten doping 20,21 .…”

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Anharmonic Lattice Dynamics in Sodium Ion Conductors

Brenner,

Grumet,

Till

et al. 2022

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We employ THz-range temperature-dependent Raman spectroscopy and first-principles latticedynamical calculations to show that the undoped sodium ion conductors Na3PS4 and isostructural Na3PSe4 both exhibit anharmonic lattice dynamics. The anharmonic effects in the compounds involve coupled host lattice -Na + ion dynamics that drive the tetragonal-to-cubic phase transition in both cases, but with a qualitative difference in the anharmonic character of the transition. Na3PSe4 shows almost purely displacive character with the soft modes disappearing in the cubic phase as the change of symmetry shifts these modes to the Raman-inactive Brillouin zone boundary. Na3PS4 instead shows order-disorder character in the cubic phase, with the soft modes persisting through the phase transition and remaining active in Raman in the cubic phase, violating Raman selection rules for that phase. Our findings highlight the important role of coupled host lattice -mobile ion dynamics in vibrational instabilities that are coincident with the exceptional conductivity in these Na + ion conductors.

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confidence: 99%

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Anharmonic Lattice Dynamics in Sodium Ion Conductors

Brenner,

Grumet,

Till

et al. 2022

Preprint

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“…The vibrations of the host lattice are, however, likely to play a role in the magnitude of 𝐸 A , as they can affect the time-averaged energetic barrier that the mobile ions must overcome. [51][52][53]…”

Section: Figure 4 Vibrational Origin Of the Isotope Effect On Activat...mentioning

confidence: 99%

Relating critical phonon occupation to activation barrier in fast lithium-ion conductors

Agne

Frerichs

Wang

et al. 2022

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Phonon-based (vibrational) theories of ion transport are likely key to developing new design strategies for solid-state ionic conductors. However, they are not often utilized because it is difficult to ascertain which vibrational frequencies are important, even in describing fundamental parameters such as the activation barrier. This is perpetuated by the fact that it is difficult to tune vibrational frequencies directly, without changing the chemical structure, in order to study underlying phonon relations. Using isotopic substitution of 6Li for 7Li, we are able to change the mobile ion vibrations in the two exemplary ion conductors Li10SnP2S12 and Li6PS5Cl without altering their structure. Using a combination of nuclear magnetic resonance spectroscopy and ab initio molecular dynamics simulations to characterize temperature-dependent ion transport, it is demonstrated that the isotopic substitution of 6Li for 7Li increases the activation barrier for Li-ion transport. The magnitude of this isotope effect cannot be explained by changes in the zero-point vibrational energy alone. Therefore, we propose that the observed change in the activation barrier is related to the differences in the average critical phonon occupation needed to overcome the activation barrier. Our hypothesis is supported by an analytical model, based on the physics of quantum harmonic oscillators, that gives good agreement with the experimental results. Thus, isotopic substitution provides unique insights into the vibrational perspective and frequency dependence of the activation barrier in fast Li-ion conductors.

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“…Another exciting class of DP applications was for Li and/or Na-based battery materials [107,[165][166][167][168][169]; here we focus on the example of Li 10 GeP 2 S 12 -type superionic conductors [107]. The DP-GEN scheme was used to generate DPs for three solid-state electrolyte materials (Li 10 GeP 2 S 12 , Li 10 SiP 2 S 12 , and Li 10 SnP 2 S 12 ) and applied to diffusion over a wide temperature range with ∼1000 atoms.…”

Section: B Multi-element Bulk Systemsmentioning

confidence: 99%

Deep Potentials for Materials Science

Wen¹,

Zhang²,

Wang³

et al. 2022

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To fill the gap between accurate (and expensive) ab initio calculations and efficient atomistic simulations based on empirical interatomic potentials, a new class of descriptions of atomic interactions has emerged and been widely applied; i.e., machine learning potentials (MLPs). One recently developed type of MLP is the Deep Potential (DP) method. In this review, we provide an introduction to DP methods in computational materials science. The theory underlying the DP method is presented along with a step-by-step introduction to their development and use. We also review materials applications of DPs in a wide range of materials systems. The DP Library provides a platform for the development of DPs and a database of extant DPs. We discuss the accuracy and efficiency of DPs compared with ab initio methods and empirical potentials.

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Fast Na diffusion and anharmonic phonon dynamics in superionic Na₃PS₄

Abstract: Strongly anharmonic low-energy phonons enable the fast diffusion of Na ions in the solid-state electrolyte compound Na3PS4.

Cited by 44 publications

References 55 publications

Anharmonic Lattice Dynamics in Sodium Ion Conductors

Anharmonic Lattice Dynamics in Sodium Ion Conductors

Relating critical phonon occupation to activation barrier in fast lithium-ion conductors

Deep Potentials for Materials Science

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Fast Na diffusion and anharmonic phonon dynamics in superionic Na3PS4

Abstract: Strongly anharmonic low-energy phonons enable the fast diffusion of Na ions in the solid-state electrolyte compound Na3PS4.

Cited by 44 publications

References 55 publications

Anharmonic Lattice Dynamics in Sodium Ion Conductors

Anharmonic Lattice Dynamics in Sodium Ion Conductors

Relating critical phonon occupation to activation barrier in fast lithium-ion conductors

Deep Potentials for Materials Science

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Fast Na diffusion and anharmonic phonon dynamics in superionic Na₃PS₄