The temperature and frequency dependent ionic conductivity in LixRb1–xPO3 glasses was studied by using dielectric spectroscopy. The direct-current conductivity decreases by more than six orders of magnitude on mixing the alkali ions in the glass structure, that is, a strong mixed alkali effect on the direct-current conductivity was observed. The results show that the mixed alkali effect on the direct-current conductivity diminishes as the temperature was increased. An alternating-current conductivity mixed alkali effect could be observed up to high frequencies, although it gradually became weaker as the frequency was increased. A quantitative analysis of the conductivity spectra showed that the number of mobile cations in the single alkali glasses is, within experimental uncertainty, temperature independent. The results were discussed in relation to a detailed microscopic structural model taking into account the random mixing of alkali ions.

Ionic Conductivity and the Mixed Alkali Effect in LixRb1–xPO3 Glasses. C.Karlsson, A.Mandanici, A.Matic, J.Swenson, L.Börjesson: Physical Review B, 2003, 68[6], 064202 (9pp)