Conductivity Of Superionic Conductors Research Articles

Ultralow Lattice Thermal Conductivity of A0.5RhO2 (A = K, Rb, Cs) Induced by Interfacial Scattering and Resonant Scattering

Recently, superionic conductors featured with melted ionic sublattices have been proved to possess ultralow thermal conductivity, but the underlying physical mechanism is under hot debate. In this article, we report ultralow out-of-plane thermal conductivity (0.4 ∼ 0.6 W m–1 K–1 at 300 K) in A0.5RhO2 (ARO, A = K, Rb, Cs) crystals with a layered structure. Analyzed by the empirical Debye–Callaway model, it reveals that both interfacial scattering and resonant scattering play dominant roles in ultralow thermal conductivity observed in RRO and CRO crystals, while in KRO crystals, resonant scattering is nearly negligible, and both interfacial scattering and three-phonon Umklapp scattering are contributed to the low thermal conductivity. Moreover, the frequency of resonant modes in ARO is dependent on ionic species, which makes it possible to modulate thermal conductivity by intercalation of different ions in the matrix. This work provides crucial information to the physical origin of ultralow thermal conductivity in superionic conductors.

Ionic Conductivity Studies in Superionic Conductors with Binary Mobile Ions Using Multi-Component Lattice Gas Model

A multi-component lattice gas model is introduced into superionic conductors. Using the model, the ionic conductivity in superionic conductors with two kinds of mobile ions is investigated. The Hamiltonian includes a repulsive interaction term and a weak hopping term for describing the interacting-ion system. It is shown that the ionic conductivity does not vary linearly with the fraction substituted and it has the minimum at an intermediate composition. This concentration dependence of the ionic conductivity qualitatively agrees with experiments performed for (Ag x Cu 1- x ) 2 Se.

Concentration Dependence of Thermal Conductivity in Superionic Conductors

By making use of the lattice gas model with a hopping term and Kubo’s formula, we have studied the mobile ion concentration dependence of the thermal conductivity in order to consider the effects of ion-ion correlation in superionic conductors. Theoretically, it is intriguing to investigate the concentration dependence of the thermal conductivity including the formulation in the framework of the lattice gas model. The thermal conductivity has symmetry with respect to ρ =0 .5, and at ρ =0a ndρ = 1 it is zero, as expected physically. The thermal conductivity first increases with the increasing concentration and has a maximum value at ρ =0 .5. It is understood that the thermal conductivity first increases with the concentration due to the increase of the repulsive interaction among the mobile ions and then takes a maximum value. Then, beyond this maximum, the thermal conductivity decreases with the concentration due to the decreasing vacancy of the ions. At ρ =0 .5, mobile ions and vacancies occupy the lattice sites alternatively.

Concentration Dependence of the Ionic Conductivity in Superionic Conductors

The dependence of the ionic conductivity on the mobile ion concentration in superionic conductors is studied by making use of the lattice gas model with a hopping term and Kubo's formula. The ionic...

Liquid-Like Model for the Ultrasonic Attenuation in Superionic Conductors: Application to α-Ag2Te

Based on the assumption that mechanisms of energy dissipation in superionic conductors and in liquids are similar in a microscopic scale, a new model for the ultrasonic attenuation in superionic conductors has been presented. The theoretical results of Rice and Allnatt for the dense fluids are used to express the viscosity and thermal conductivity in superionic conductors. The cage sublattice is considered by introducing a heavy ion mass, which conveniently characterizes immobile lattice ions when the system is observed from the viewpoint of the liquid theory. The model has been applied to superionic conductor α-Ag 2 Te to obtain the coefficients of viscosity and of ultrasonic attenuation, and the results showed that the model was sufficiently promising. According to this model, the main mechanism for the ultrasonic attenuation is the hard core collisions between the mobile ions and the surrounding lattice ions.

Thermal conduction by mobile ions in superionic conductors

The contribution of mobile ions to the thermal conductivity in superionic conductors is investigated by making use of the lattice gas model with a hopping term. The thermal conductivity is obtained as a function of ion concentration and repulsive interaction energy between the nearest neighbors. It is shown that the contribution of mobile ions to the thermal conductivity is of an Arrhenius type in the usual temperature region in which measurements are conducted.

Thermal conductivity in superionic conductors

The contribution of mobile ions to the thermal conductivity in superionic conductors is investigated by making use of the lattice gas model with a hopping term. The thermal conductivity is obtained as a function of an ion concentration and a repulsive interaction energy between the nearest neighbors. It is shown that the contribution of mobile ions to the thermal conductivity is of an Arrhenius type in the usual temperature region in which measurements are conducted.

Dynamic conductivity of superionic conductors in an interacting Brownian particle model

The mobile ion dynamics in superionic conductors is described by a many-particle Fokker-Planck equation. A time-dependent mean-field equation for the single-particle distribution is derived, which implies a general relationship between the dynamic conductivity and structural properties. We find that the low-frequency diffusive regime is governed by a renormalized single-particle potential, whereas the high-frequency vibrational response is determined by the bare interaction between the two species of conducting and lattice ions. Numerical results, based on matrix continued fractions are presented for the whole frequency-range and implications with respect to experiments are discussed.

Conductivity of a generalized hopping system with internal dynamics

We derive explicit exact expressions for the frequency dependent conductivity of a system whose dynamics is described by a Master Equation in which the transition ratesΓab can be functions of other dynamical variables. We apply this method to study the hopping of particles in a lattice with the hopping rate modulated by an additional harmonic variable. The results of this model are related to the observed microwave conductivity of superionic conductors. In particular we show that the modulation of the hopping rate can produce a structure similar to the one observed in AgI type systems.