Abstract
Variable-pressure, variable-temperature (VPVT) measurements of ionic conductivity in typical inorganic (sodium aluminoborate and lithium-sodium phosphate) glasses provide information concerning two independent activation parameters: the activation energy (E-A = -R d ln sigmaT/d(1/T)) and the activation volume (V-A = -RT d ln sigma/dP). In single-cation glasses there is no simple link between E-A and V-A. The strong increase in E-A seen with decreasing alkali content is not paralleled by an increase in V-A. However, in mixed cation glasses, maxima are observed in both E-A and V-A. To account for these observations, a new model is being developed where ion transport is limited by a shortage of available volume. In this model, the measured V-A values represent the volumes of opened up 'target sites', the larger values observed in mixed-cation glasses providing evidence for the coupled motion of unlike ions. The extent of this pairwise coupling increases with increasing temperature.
Original language | English |
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Pages (from-to) | 3067-3070 |
Number of pages | 4 |
Journal | Dalton Transactions |
Volume | 2004 |
Issue number | 19 |
Early online date | 26 Jul 2004 |
DOIs | |
Publication status | Published - 2004 |
Bibliographical note
We express our thanks to K. Funke and R. Banhatti (University of Münster) for helpful discussions, while one of us (I. K.) thanks EPSRC and the University of Aberdeen for financial support. M. D. I. thanks the Alexander von HumboldtFoundation for the receipt of a Research Award.