Decoupling charge transport from the structural dynamics in room temperature ionic liquids

被引：67

作者：

Griffin, Philip ^{[1
]}

Agapov, Alexander L. ^{[4
]}

Kisliuk, Alexander ^{[3
]}

Sun, Xiao-Guang ^{[3
]}

Dai, Sheng ^{[2
,3
]}

Novikov, Vladimir N. ^{[2
,3
,5
]}

Sokolov, Alexei P. ^{[1
,2
,3
]}

机构：

[1] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA

[2] Univ Tennessee, Dept Chem, Knoxville, TN 37996 USA

[3] Oak Ridge Natl Lab, Div Chem Sci, Oak Ridge, TN 37830 USA

[4] Univ Akron, Dept Polymer Sci, Akron, OH 44325 USA

[5] Russian Acad Sci, IA&E, Novosibirsk 630090, Russia

来源：

JOURNAL OF CHEMICAL PHYSICS | 2011年 / 135卷 / 11期

基金：

美国国家科学基金会;

关键词：

GLASS-FORMING LIQUIDS; PHYSICOCHEMICAL PROPERTIES; HETEROGENEOUS DYNAMICS; DIELECTRIC-RELAXATION; MOLECULAR-WEIGHT; SELF-DIFFUSION; TRANSITION; VISCOSITY; CROSSOVER; SUPERPOSITION;

D O I：

10.1063/1.3638269

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward T-g. The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be T-c similar to 225 +/- 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process. (C) 2011 American Institute of Physics. [doi:10.1063/1.3638269]

引用

页数：8

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