Electronic and ionic conductivities in superionicLi4C60

Abstract

The 10 GHz microwave conductivity, σ(T ) and high field, 222 GHz electron spin resonance (HF-ESR) of Li4C60 fulleride is measured in a wide temperature range. We suggest that the majority of ESR active sites and at least some of the charge carriers for σ(T ) are electrons bound to a small concentration of surplus or vacancy ions in the polymer phase. Both σ(T ) and the ESR line shape depend on ionic motion. A change of the activation energy of σ(T ) at 125 K coincides with the onset of the ionic DC conductivity. The ESR line shape is determined mainly by Li ionic motion within octahedral voids below 150 K. At higher temperatures, fluctuations due to ionic diffusion change the environment of defects from axial to effectively isotropic on the ESR time scale. σ(T ) data up to 700 K through the depolymerization transition confirm that the monomeric phase of Li4C60 is a metal.

Generalized Hertz Vector in the Dissipative Electrodynamics

“…We hope that based on the presented Lagrangian formulation, the electromagnetic and the thermal fields can couple, by which further studies may be possible in the case of electromagnetic radiation in media. We believe that beyond the mentioned cases in the motivation [2][3][4][5][6][7][8][9][10], the method can even be extended to materials with magnetic behavior [31].…”

“…The microwave cavity perturbation experiments [1], are generally used to explore the material structure measuring the resonance frequency [2]. Wide range of electric conductive novel materials can be studied like Li 4 C 60 superionic conductor [3], single wall carbon nanotubes [4], with these high accuracy measurements [5]. It seems that this experimental setup is applicable to study superconductor powders [6].…”

A First-Principles Investigation of Lithium and Sodium Ion Diffusion in C60 Molecular Solids

“…In the solid-state, C 60 molecules form a face centered cubic (FCC) molecular crystal, and solid-state C 60 finds use as components in photovoltaics, supercapacitors, photomasks, and lubricants . When intercalated with alkali and alkali earth ions, solid state C 60 is known to exhibit composition-dependent superconductivity, tunable optical properties, room temperature high ZT thermoelectricity, and notably, superionic conductivity. − However, the high ionic conductivity of lithium-doped crystalline C 60 is a point of contention and pertinent investigations have shown that electronic and mixed electronic–ionic contributions need to be considered as well. , Thus, despite past valuable experimental and simulation investigations, fundamental questions still remain on the extent of ionic conductivity and the underlying diffusive pathways that dictate ionic motion in C 60 solids . Unraveling such questions can shed further light on the utility of C 60 structures as potential components of alkali ion batteries, especially since there have been past efforts in integrating them both as electrode materials as well as interphase materials for ensuring the interfacial integrity of electrodes in lithium-ion batteries (LIB).…”

“…8−10 However, the high ionic conductivity of lithiumdoped crystalline C 60 is a point of contention and pertinent investigations have shown that electronic and mixed electronic−ionic contributions need to be considered as well. 11,12 Thus, despite past valuable experimental and simulation investigations, fundamental questions still remain on the extent of ionic conductivity and the underlying dif f usive pathways that dictate ionic motion in C 60 solids. Unraveling such questions can shed further light on the utility of C 60 structures as potential components of alkali ion batteries, especially since there have been past efforts in integrating them both as electrode materials 13 as well as interphase materials 14 for ensuring the interfacial integrity of electrodes in lithium-ion batteries (LIB).…”