AC conductivity and electrical relaxation studies on 10CuI-60AgI-30V<inf>2</inf>O<inf>5</inf> glasses

The ac response of glasses in the 10CuI-60Ag2O-30V2O5 glasses has been measured in terms of real and imaginary parts of the impedance in the frequency range 5 Hz to 13 MHz and analyzed in admittance, permittivity and modulus formalisms. Frequency-dependent conductivity obeys universal power-law behaviour σ(ω) = σ(0)+Aω+n$/, where n and A are constants in the temperature range studied. The real part of dielectric permittivity, ε′ shows a saturation at higher frequencies and a strong dispersion at lower frequencies. The imaginary part of the permittivity, ε″ varies inversely with frequency, due to the presence of dc conductivity σ(0). Loss peak could be observed after subtracting from ε″, the contribution due to dc conductivity. The frequency variation of the imaginary part M″ of the complex electric modulus M* is found to be broader than that observed in the case of a single relaxation phenomenon (Debye type). The peak positions ω-m$/ of the above spectra shift towards higher frequencies with increase in temperature. The above spectra have been characterized in terms of Kohlrausch-William-Watts (KWW) relaxation function to understand relaxation behaviour. The overlap of plots of normalized M″ versus frequency at various temperatures reveals that the distribution of relaxation time is independent of temperature.