Anharmonic lattice dynamics of superionic lithium nitride

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 fully anharmonic model, however, exhibits a phonon breakdown for all modes above the superionic transition temperature. The implications for developing lattice-dynamics based descriptors for superionic conductors are discussed.

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Anharmonic lattice dynamics of superionic lithium nitride

Journal of Materials Chemistry A ◽

10.1039/d1ta07631k ◽

2021 ◽

Author(s):

Gabriel Krenzer ◽

Chang Eun Kim ◽

Kasper Tolborg ◽

Benjamin Morgan ◽

Aron Walsh

Keyword(s):

High Temperature ◽

Ionic Conductivity ◽

Lattice Dynamics ◽

Lithium Nitride ◽

Physical Mechanisms ◽

Liquid Electrolytes ◽

Anharmonic Lattice ◽

Superionic Transition

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Argon Thermal Conductivity by Anharmonic Lattice Dynamics Calculations

Heat Transfer: Volume 1 ◽

10.1115/ht2008-56146 ◽

2008 ◽

Author(s):

J. E. Turney ◽

A. J. H. McGaughey ◽

C. H. Amon

Keyword(s):

Thermal Conductivity ◽

Thermal Transport ◽

Lattice Dynamics ◽

Mode Shapes ◽

Face Centered Cubic ◽

Phonon Modes ◽

Anharmonic Lattice ◽

The Face ◽

Face Centered ◽

Dynamics Simulations

Lattice dynamics calculations are used to investigate thermal transport in the face-centered cubic Lennard-Jones (LJ) argon crystal between temperatures of 20 and 80 K. First, quasi-harmonic lattice dynamics calculations are used to find the frequencies and mode shapes of non-interacting phonons [1]. This information is then used as input for anharmonic lattice dynamics calculations. Anharmonic lattice dynamics is a means of computing the frequency shift and lifetime of each phonon mode due to interactions with other phonons [2]. The phonon frequencies, group velocities, and lifetimes, determined with the lattice dynamics methods, are then used to compute the thermal conductivity. The thermal conductivities predicted by the lattice dynamics methods are compared to predictions from molecular dynamics simulations. The two methods are found to agree well at low temperature but diverge at higher temperatures (i.e., near the melting point). The properties of individual phonon modes are used to identify the modes that dominate thermal transport.

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Dynamic disorder phonon scattering mediated by Cu atomic hopping and diffusion in Cu3SbSe3

npj Computational Materials ◽

10.1038/s41524-020-00421-4 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Chen Wang ◽

Yixuan Wu ◽

Yanzhong Pei ◽

Yue Chen

Keyword(s):

Nearest Neighbor ◽

Elevated Temperatures ◽

Phonon Scattering ◽

Low Cost ◽

Phonon Transport ◽

Ab Initio Molecular Dynamics ◽

Phonon Modes ◽

Tetrahedral Framework ◽

Superionic Transition ◽

The Relationship

Abstract Cu3SbSe3 that exhibits distinct liquid-like sublattice due to the heterogeneous bonding environment has emerged as a promising low cost superionic semiconductor with intrinsic ultralow thermal conductivity. However, the relationship between atomic dynamics resulting in liquid-like diffusion and anomalous phonon transport properties remains poorly understood. Herein, combing ab initio molecular dynamics with temperature-dependent Raman measurements, we have performed a thorough investigation on the lattice dynamics of Cu3SbSe3. Superionic transition is unveiled for both structurally inequivalent Cu atoms at elevated temperatures, while the Se-formed tetrahedral framework can simultaneously maintain. An intermediate state of Cu3SbSe3 through the mixture of quasi-1D/2D Cu nearest-neighbor vacancy hopping is discovered below the superionic transition temperature. Our results also manifest that phonons predominately involved with Cu contributions along diffusion channels have been strongly scattered during the superionic transition, whereas the liquid-like diffusion of Cu is too slow to completely breakdown the propagation of all transverse phonon modes. The insight provided by this work into the atomic dynamics and phonon scattering relationship may pave the way for further phonon engineering of Cu3SbSe3 and related superionic materials.

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Anharmonic lattice dynamics and superionic transition in AgCrSe2

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1913916117 ◽

2020 ◽

Vol 117 (8) ◽

pp. 3930-3937 ◽

Cited By ~ 9

Author(s):

Jingxuan Ding ◽

Jennifer L. Niedziela ◽

Dipanshu Bansal ◽

Jiuling Wang ◽

Xing He ◽

...

Keyword(s):

Thermal Conductivity ◽

Short Wavelength ◽

Lattice Dynamics ◽

Spectral Weight ◽

Superionic Conductors ◽

Long Wavelength ◽

Anharmonic Lattice ◽

Transverse Acoustic ◽

Strong Repulsion ◽

Energy And Momentum

Intrinsically low lattice thermal conductivity (κlat) in superionic conductors is of great interest for energy conversion applications in thermoelectrics. Yet, the complex atomic dynamics leading to superionicity and ultralow thermal conductivity remain poorly understood. Here, we report a comprehensive study of the lattice dynamics and superionic diffusion in AgCrSe2 from energy- and momentum-resolved neutron and X-ray scattering techniques, combined with first-principles calculations. Our results settle unresolved questions about the lattice dynamics and thermal conduction mechanism in AgCrSe2. We find that the heat-carrying long-wavelength transverse acoustic (TA) phonons coexist with the ultrafast diffusion of Ag ions in the superionic phase, while the short-wavelength nondispersive TA phonons break down. Strong scattering of phonon quasiparticles by anharmonicity and Ag disorder are the origin of intrinsically low κlat. The breakdown of short-wavelength TA phonons is directly related to the Ag diffusion, with the vibrational spectral weight associated to Ag oscillations evolving into stochastic decaying fluctuations. Furthermore, the origin of fast ionic diffusion is shown to arise from extended flat basins in the energy landscape and collective hopping behavior facilitated by strong repulsion between Ag ions. These results provide fundamental insights into the complex atomic dynamics of superionic conductors.

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Influence of Structural Distortion and Lattice Dynamics on Li-Ion Diffusion in Li3OCl1–xBrx Superionic Conductors

ACS Applied Energy Materials ◽

10.1021/acsaem.0c02519 ◽

2021 ◽

Author(s):

Ronghan Chen ◽

Zhenming Xu ◽

Yuechuan Lin ◽

Buyao Lv ◽

Shou-Hang Bo ◽

...

Keyword(s):

Lattice Dynamics ◽

Structural Distortion ◽

Superionic Conductors ◽

Ion Diffusion ◽

Li Ion

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Anharmonic lattice dynamics ofAg2Ostudied by inelastic neutron scattering and first-principles molecular dynamics simulations

Physical Review B ◽

10.1103/physrevb.89.054306 ◽

2014 ◽

Vol 89 (5) ◽

Cited By ~ 23

Author(s):

Tian Lan ◽

Chen W. Li ◽

J. L. Niedziela ◽

Hillary Smith ◽

Douglas L. Abernathy ◽

...

Keyword(s):

Molecular Dynamics ◽

Neutron Scattering ◽

Molecular Dynamics Simulations ◽

First Principles ◽

Lattice Dynamics ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Anharmonic Lattice ◽

Dynamics Simulations ◽

First Principles Molecular Dynamics

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Non-affine lattice dynamics of defective fcc crystals

Soft Matter ◽

10.1039/c7sm00843k ◽

2017 ◽

Vol 13 (36) ◽

pp. 6079-6089 ◽

Cited By ~ 4

Author(s):

Johannes Krausser ◽

Rico Milkus ◽

Alessio Zaccone

Keyword(s):

State Physics ◽

Solid State ◽

Lattice Dynamics ◽

Soft Matter ◽

Vibrational Properties ◽

Solid State Physics ◽

Colloidal Physics ◽

Defective Crystals

The mechanical, thermal and vibrational properties of defective crystals are important in many different contexts, from metallurgy and solid-state physics to, more recently, soft matter and colloidal physics.

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Phonons transmission through atomic interface connecting two semi-infinite 2D lattices with different meshes

International Journal of Modern Physics B ◽

10.1142/s0217979222500126 ◽

2021 ◽

Author(s):

Smail Sait ◽

Boualem Bourahla

Keyword(s):

Lattice Dynamics ◽

Scattering Matrix ◽

Model Structure ◽

Coherent Phonon ◽

Elastic Coupling ◽

Phonon Modes ◽

Coherent Transport ◽

Coherent Coupling ◽

Discrete States ◽

Matching Technique

A calculation of the phonon contribution to the coherent transport between two-dimensional (2D) lattices is presented in this paper. The model structure is obtained by the juxtaposition of semi-infinites square ([Formula: see text] and triangular ([Formula: see text] leads, which thus define the nanojunction [Formula: see text]/[Formula: see text] and its inverse [Formula: see text]/[Formula: see text]. We determine, numerically and by simulation, the 2D interface observables for different values of masses and elastic coupling in the nanojunction zone. The local dynamics and atomic nanojunction response to the microscopic changes, in the interfacial domain, are subjects to our investigation. The theoretical formalism based on the matching technique is applied to describe the lattice dynamics and the evanescent phonon modes, in the two studied 2D interfaces. We mainly analyze the vibration spectra, the coherent phonon transmission/reflection and the phononic transmittance through the interface, as elements of a Landauer–Büttiker type scattering matrix. The obtained results show that the nanojunction domain is an effective phonon splitter and suggest that its characteristics may be controlled by varying its nanometric parameters. The observed fluctuations are due to the coherent coupling between continuum modes and the phonons’ discrete states induced by the connected atomic sites.

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