Analysis of electrical relaxation in glasses and melts with large concentrations of mobile ions

Abstract

Various analyses of or fits to electrical relaxation data for a model Li 2OAl 2O 32SiO 2 glass s were tried. These included three-parameter fits using Kohlrausch-Williams-Watts (KWW) and Cole-Davidson (CD) distributions of electric field relaxation times, along with a four-parameter σ ′( ω n ) fit using the distribution implicitin the Jonscher expression for the frequency dependence of the real part of the complex conductivity, σ ′ = σ + Aω n . In the frequency range 10 −2 ≤ ω < τ> ≤10 2, where <τ> is the mean electric field relaxation time, the KWW firt was best, the σ ′( ω n ) fit second best and the CD fit the worst. Because the σ ′( ω n ) fit predicts qualitattively incorrect relaxation behavior at low frequencies, it is suggested that this method of data analysis not be used. It was noted that the dependence of σ ′ on ω 1 observed for ionically conducting solids at very high frequencies or very low temperatures make a nearly negligible contribution to the relaxation of the electric field.