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Cage decay, near constant loss, and crossover to cooperative ion motion in ionic conductors: insight from experimental data

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Ngai, K. L. and León Yebra, Carlos (2002) Cage decay, near constant loss, and crossover to cooperative ion motion in ionic conductors: insight from experimental data. Physical review B, 66 (6). ISSN 1098-0121

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Official URL: http://dx.doi.org/10.1103/PhysRevB.66.064308


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Abstract

Experimental frequency-dependent conductivity relaxation spectra of a number of molten, glassy, and crystalline ionic conductors that show both the presence of the near constant loss (NCL) and the cooperative ion hopping contribution are analyzed. On decreasing frequency, the NCL appears first but terminates at some frequency v_(x1). At still a lower frequency v_(x2) the cooperative ion hopping dispersion takes over. The independent ion hopping frequency v_(0) of the coupling model is calculated from the parameters characterizing the cooperative ion hopping dispersion. It is found for all ionic conductors that v_(x1)>>v_(0), and v_(0) always fall inside the frequency region v_(x1) > v > v_(x2). The empirical results leads to a qualitative theory for the origin of the NCL, which gives physical meanings of the two crossover frequencies v_(x1) and v_(x2), as well as explaining the role of the independent hopping frequency v_(0), in determining them. The weak temperature dependence of the NCL has been recaptured by the qualitative theory. An improved understanding is gained of the evolution of the ion dynamics from early times when the cages decay very slowly with time, giving rise to the near constant loss, to long times when ions move cooperatively, leading finally to dc conductivity.


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Additional Information:

© 2002 The American Physical Society. We thank P. Lunkenheimer, A. Kulkarni, A. Pradel, C. Cramer, and H. Jain for sending their experimental data. The work performed at NRL was supported by ONR. C. León is supported in Spain by CICYT Grant No. MAT2001-3713- C04.

Uncontrolled Keywords:Glass transformation temperature; Complete conductivity spectra; Yttria-stabilized zirconia; Iodide-silver selenate; AC-conductivity; Neutron-scattering; Light-scattering; Sctructural relaxation; Electrical relaxation; Chalcogenide glasses.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:31075
Deposited On:26 Jun 2015 07:23
Last Modified:10 Dec 2018 14:58

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