Electrical relaxation in CdI₂ doped silver vanadate superionic glasses

Abstract

In this paper we have studied electrical relaxation in several compositions of CdI₂-Ag₂O-V₂O₅ superionic glasses in wide frequency and temperature ranges. We have used the power law formalism as well as the electric modulus formalism to analyze the experimental results. We have observed that the dc conductivity increases and the activation energy decreases with the increase of the CdI₂ content in the compositions. We have also observed that the concentration of mobile Ag⁺ ions is not thermally activated and is almost independent of CdI₂ content. The mobile ion concentration is also less than that of the total Ag⁺ ions present in the compositions. The conductivity is primarily determined by the mobility rather than the ion concentration. The conductivity relaxation time shows Arrhenius behavior with an activation energy, which is almost equal to that of the dc conductivity, indicating that the same ions take part in the dc and the ac conduction. The values of frequency exponent and stretching exponent are observed to be almost temperature and composition independent. The exponents are less than unity and obey the relationship proposed by Ngai.