Selective breakdown of phonon quasiparticles across superionic transition in CuCrSe <inf>2</inf>
Abstract
© 2018, The Author(s), under exclusive licence to Springer Nature Limited. Superionic
crystals exhibit ionic mobilities comparable to liquids while maintaining a periodic
crystalline lattice. The atomic dynamics leading to large ionic mobility have long
been debated. A central question is whether phonon quasiparticles—which conduct heat
in regular solids—survive in the superionic state, where a large fraction of the system
exhibits liquid-like behaviour. Here we present the results of energy- and momentum-resolved
scattering studies combined with first-principles calculations and show that in the
superionic phase of CuCrSe 2 , long-wavelength acoustic phonons capable of heat conduction
remain largely intact, whereas specific phonon quasiparticles dominated by the Cu
ions break down as a result of anharmonicity and disorder. The weak bonding and large
anharmonicity of the Cu sublattice are present already in the normal ordered state,
resulting in low thermal conductivity even below the superionic transition. These
results demonstrate that anharmonic phonon dynamics are at the origin of low thermal
conductivity and superionicity in this class of materials.
Type
Journal articleSubject
Science & TechnologyPhysical Sciences
Physics, Multidisciplinary
Physics
ULTRALOW THERMAL-CONDUCTIVITY
TOTAL-ENERGY CALCULATIONS
NEUTRON-SCATTERING
THERMOELECTRIC PERFORMANCE
TRANSPORT
LIQUID
DIFFUSION
CONDUCTORS
DYNAMICS
ORIGIN
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https://hdl.handle.net/10161/20065Published Version (Please cite this version)
10.1038/s41567-018-0298-2Publication Info
Niedziela, Jennifer; Bansal, Dipanshu; May, Andrew; Ding, Jingxuan; Lanigan-Atkins,
Tyson; Ehlers, Georg; ... Delaire, Olivier (2019). Selective breakdown of phonon quasiparticles across superionic transition in CuCrSe
<inf>2</inf>. Nature Physics, 15(1). pp. 73-78. 10.1038/s41567-018-0298-2. Retrieved from https://hdl.handle.net/10161/20065.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Olivier Delaire
Associate Professor of Mechanical Engineering and Materials Science
The Delaire group investigates atomistic transport processes of energy and charge,
and thermodynamics in energy materials. We use a combined experimental and computational
approach to understand and control microscopic energy transport for the design of
next-generation materials, in particular for sustainable energy applications. Current
materials of interest include superionic conductors, photovoltaics, thermoelectrics,
ferroelectrics/multiferroics, and metal-insulator transitions. Our group

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