Composition dependence of frequency power law of ionic conductivity of glasses

The electrical response of three potassium germanate glasses, xK(2)O:(1-x)GeO2, where x = 0.0023, 0.02 and 0.20, has been investigated between room temperature and 700 K as a function of frequency (10 Hz-100 kHz). The frequency dependence of ionic conductivity of the high alkali content glass shows typical characteristics of the universal dynamic response (UDR): a dc plateau followed by a power law of frequency with an exponent s similar to 0.5-0.6. However, as the mobile ion concentration approaches zero, the UDR frequency region and the conductivity dispersion in the vicinity of dc relaxation time disappear i.e. the Kohlrausch parameter becomes unity.