Nearly constant dielectric loss of glasses containing different mobile alkali ions

Abstract Recently, Rivera et al. [Phys. Rev. Lett. 88 (2002) 125902] found that the magnitude of the nearly constant dielectric loss (NCL) in alkali triborate glasses decreases as m −1/3 with increasing alkali ion mass m . We have carried out conductivity measurements on aluminosilicate and aluminogermanate glasses containing different mobile alkali ions, and we show that the magnitude of the NCL does not follow a m −1/3 relation. Instead, we find a strong correlation between the magnitude of the NCL, the dc conductivity, and the dielectric relaxation strength which is valid for various ionic glasses at temperatures above 173 K.