ION AND POLARON CONDUCTING GLASSES

Conductivity spectra, sigma(omega), covering wide frequency ranges up to the mid infrared, have been taken of various glasses at different t emperatures. The systems studied include the ion-conducting glasses 0. 30 Na2O . 0.70 B2O3, 0.30 Li2O . 0.70 B2O3 and B2O3 . 0.56 Li2O . 0.45 LiBr as well as the polaron conducting glass 0.2 P2O5 . 0.8 (0.89 V2O 5 . 0.11 V2O4). In the case of the ion-conducting glasses it is possib le to separate vibrational and hopping spectra from each other. The re sulting hopping spectra display high-frequency plateaus; in the disper sive regime, two power-law exponents are observed, one being smaller, the other larger than unity. In contrast, the dispersive conductivity of the polaron conducting glass shows a simple single-power-law behavi or with an exponent smaller than one. The interpretation of the spectr a includes the idea of different ''target'' sites for the mobile speci es. A model concept for ion and polaron transport in glasses is propos ed.