Phonon quasiparticles and their anharmonic interactions govern heat transport in insulators.Accurate characterization of phonon frequencies and linewidths,especially beyond the quasiparticle approximation,is essential...Phonon quasiparticles and their anharmonic interactions govern heat transport in insulators.Accurate characterization of phonon frequencies and linewidths,especially beyond the quasiparticle approximation,is essential for understanding anharmonic effects and lattice thermal conductivity.Here,we investigate the anharmonic lattice dynamics and phonon transport in crystalline copper halides CuBiI_(4) using the self-consistent phonon theory,combined with the Wigner transport formalism and the quasi-harmonic Green–Kubo method.Results show that the three-phonon bubble self-energy substantially renormalizes the phonon dispersion,inducing strong modedependent broadening.Depending on the strength of the anharmonic scattering,phonons exhibit particle-like,wave-like,or overdamped transport characteristics,with broadened states contributing additional coherent thermal transport channels.We establish a consistent description of the overdamped phonon self-energy and advance the microscopic understanding of the strongly anharmonic phonon thermal transport in CuBiI_(4).Overdamped phonon modes significantly hinder the lattice thermal transport by reducing phonon lifetimes.However,the still well-defined phonon dispersions mitigate carrier scattering induced by the local structural disorder.Anisotropic electrical transport properties are obtained by considering polar and non-polar electroacoustic coupling and ionized impurity scattering mechanisms.Upon electron doping,the thermoelectric figure of merit of n-type CuBiI_(4) reaches 2.25 at 800 K.展开更多
In the realm of lithium superionic conductors,pursuing higher ionic conductivity is imperative,with the variance in lithium-ion concentration playing a determining role.Due to the permanent and temporary site-blocking...In the realm of lithium superionic conductors,pursuing higher ionic conductivity is imperative,with the variance in lithium-ion concentration playing a determining role.Due to the permanent and temporary site-blocking effects,especially at non-dilute concentrations,not all Li-ions contribute to ionic conductivity.Here,we propose a strategy to directly calculate effective mobile ion concentration in which multiple-ion correlated migration is considered in the percolation analysis with the input of Li-ion distributions and hopping behavior based on kinetic Monte Carlo simulation,termed P-KMC.We provide examples of two representative lithium superionic conductors,cubic garnet-type LixA3B2O12(0≤x≤9;A and B represent different cations)and perovskite-type LixLa2/3−x/3TiO3(0≤x≤0.5),to demonstrate the direct dependence of the ionic conductivity on the effective mobile ion concentration.This methodology provides a robust tool to identify the optimal compositions for the highest ionic conductivity in superionic conductors.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12574028,U2330104,and 12074381)Guang-dong Basic and Applied Basic Research Foundation(Grant No.2024A1515010484)。
文摘Phonon quasiparticles and their anharmonic interactions govern heat transport in insulators.Accurate characterization of phonon frequencies and linewidths,especially beyond the quasiparticle approximation,is essential for understanding anharmonic effects and lattice thermal conductivity.Here,we investigate the anharmonic lattice dynamics and phonon transport in crystalline copper halides CuBiI_(4) using the self-consistent phonon theory,combined with the Wigner transport formalism and the quasi-harmonic Green–Kubo method.Results show that the three-phonon bubble self-energy substantially renormalizes the phonon dispersion,inducing strong modedependent broadening.Depending on the strength of the anharmonic scattering,phonons exhibit particle-like,wave-like,or overdamped transport characteristics,with broadened states contributing additional coherent thermal transport channels.We establish a consistent description of the overdamped phonon self-energy and advance the microscopic understanding of the strongly anharmonic phonon thermal transport in CuBiI_(4).Overdamped phonon modes significantly hinder the lattice thermal transport by reducing phonon lifetimes.However,the still well-defined phonon dispersions mitigate carrier scattering induced by the local structural disorder.Anisotropic electrical transport properties are obtained by considering polar and non-polar electroacoustic coupling and ionized impurity scattering mechanisms.Upon electron doping,the thermoelectric figure of merit of n-type CuBiI_(4) reaches 2.25 at 800 K.
基金supported by the National Natural Science Foundation of China(Nos.92270124,52102313,92472207)the Hunan Provincial Natural Science Foundation of China(No.2023JJ40635)+1 种基金Shandong Province Natural Science Foundation(No.ZR2022ZD11)the High-Performance Computing Center of Shanghai University and Shanghai Engineering Research Center of Intelligent Computing Systems for providing computing resources and technical support.
文摘In the realm of lithium superionic conductors,pursuing higher ionic conductivity is imperative,with the variance in lithium-ion concentration playing a determining role.Due to the permanent and temporary site-blocking effects,especially at non-dilute concentrations,not all Li-ions contribute to ionic conductivity.Here,we propose a strategy to directly calculate effective mobile ion concentration in which multiple-ion correlated migration is considered in the percolation analysis with the input of Li-ion distributions and hopping behavior based on kinetic Monte Carlo simulation,termed P-KMC.We provide examples of two representative lithium superionic conductors,cubic garnet-type LixA3B2O12(0≤x≤9;A and B represent different cations)and perovskite-type LixLa2/3−x/3TiO3(0≤x≤0.5),to demonstrate the direct dependence of the ionic conductivity on the effective mobile ion concentration.This methodology provides a robust tool to identify the optimal compositions for the highest ionic conductivity in superionic conductors.
