IONIC AND POLARONIC GLASSY CONDUCTORS - CONDUCTIVITY SPECTRA AND IMPLICATIONS FOR IONIC HOPPING IN GLASS

Complete conductivity spectra have been taken of a lithium ion and a p olaron conducting glass. The former exhibits high-frequency plateaux i n its hopping conductivities and two different power-law exponents in the dispersive regime. This is readily explained if ions, contrary to polarons, have a pronounced site preference. At the same time, this vi ew also explains the well known differences in the dependence of carri er mobility on carrier concentration in the two types of glasses.