Dielectric spectra of Li2O–CaF2–P2O5 glasses doped by silver ions

Dielectric constant ε′, loss tan δ and a.c. conductivity σ(ω) Li2O–CaF2–P2O5 glasses doped with small concentrations of Ag2O (ranging from 0 to 1.0 mol%) are studied as a function of frequency and temperature over moderately wide ranges. The variation of dielectric loss with temperature for these glasses has exhibited dielectric relaxation effects. The relaxation effects have been analyzed by a pseudo Cole–Cole plot method and the spreading of relaxation times has been established. The variation of a.c. conductivity with the concentration of Ag2O pass through a minimum at 0.6 mol% Ag2O. In the high-temperature region, the a.c. conduction seems to be connected with the mixed conduction, viz., electronic and ionic conduction. The low-temperature part of the a.c. conductivity which is observed to be nearly temperature independent has been explained on the basis of quantum mechanical–tunneling (QMT) model. The results have been further analyzed in detail with the aid of the data on optical absorption, IR and Raman spectral studies.