| Title: | STOCHASTIC MODELING OF ION DYNAMICS IN GLASSES |
| DOI No: | 10.1142/9789812776259_0082 |
| Source: | SOLID STATE IONICS
Trends in the New Millennium (pp 689-700)
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| Author(s): | W. DIETERICH
Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
P. MAASS
Institut für Physik, Technische Universität Ilmenau, 98684 Ilmenau, Germany
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| Abstract: | Network glasses doped with alkali ions show peculiar dc-transport and dynamic properties detected in diffusion and conductivity studies, nuclear spin relaxation, quasielastic neutron scattering and ultrasonic experiments. Prominent features observerd in many glasses are a sensitive dependence of the dc-conduction on composition in single-ion glasses, mixed alkali effects and "quasi-universal" behaviour in various ac-measurements. Recently, a "nearly constant loss" (NCL) in dielectric relaxation spectroscopy was found as a second universal feature in the dynamic response of ionic glasses. Such properties are well described by many-particle stochastic lattice gas models based on site-energy disorder and Coulomb interactions. Fundamental implications of long-range Coulomb forces among the moving ions and with immobile counterions are analyzed by means of Monte Carlo simulations and are related to experiments. We will show that the counterion model bears a mechanism for an NCL-type response, which in this way is interpreted as a result of correlated dipolar reorientation processes. In addition, we present theoretical concepts for the understanding of mixed-alkali effects and indicate ideas how to combine such concepts with counterion effects. |
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