Berlin 2005 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 8: Gl
äser II (gemeinsam mit FV DY)
DF 8.11: Vortrag
Montag, 7. März 2005, 17:15–17:30, TU A060
Pressure dependent ionic conductivity of sodium-rubidium borate glasses — •Árpád W. Imre1, Stephan Voss1,2, Ioannis Konidakis3, Frank Berkemeier1, Malcolm Ingram3, and Helmut Mehrer1 — 1Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Str.10, D-48149 Münster, Germany — 2now at: Infineon Technologies, München, Germany — 3Department of Chemistry, University of Aberdeen UK AB24 3UE
Measurements of the ionic conductivity as a function of pressure have been performed in a series of 0.3[X Na2O·(1−X)Rb2O]·0.7 B2O3 mixed- and single-alkali borate glasses. The activation volumes of the electrical conductivity are obtained at 453 K. The following fingerprints of the mixed-alkali effect were observed earlier in these glasses: i) the glass-transition temperature has a minimum near X = 0.2, ii) the diffusivities of 22Na and 86Rb crossover near X = 0.2, iii) the ionic conductivity σdc shows a minimum with composition near X = 0.4, iv) the activation enthalpy of σdc times temperature has a maximum near X = 0.4. As an additional feature of the mixed-alkali effect a maximum in the activation volume was found close to X = 0.4. The activation volumes obtained in the case of single-alkali borate glasses compare well with the corresponding ionic volumes for Na and Rb, respectively. In the single-alkali glasses the activation volume shows a constant behavior as a function of alkali content.