AC conductivity and dielectric properties of 98[20Li2O-xBi2O3-(80-x)TeO2]-2Ag mixed ionic-electronic glasses

Mixed ionic-electronic 98[20Li(2)O-xBi(2)O(3)-(80-x)TeO2]-2Ag (x = 3, 5, 7, 11, 13 and 15 mol%) glasses were prepared by melt-quenching technique to investigate their AC conductivity and dielectric properties. Structural analysis revealed the increase of non-bridging oxygen (NBO) up to x = 5 mol% before dropping at x = 7 mol% followed by a further increase at x > 7 mol%. The nonlinear behaviour of AC conductivity with Bi2O3 showed an initial increase in sigma(AC) until reaching a minimum at x = 7 and 11 mol% before increasing again at x > 11 mol%. The minimum is suggested to be due to the blocking effects of Bi2O3 towards ionic conduction caused by mixed ionic-electronic (MIE) effect. Other than that, dielectric constant displayed an anomalous decrease at x = 7 mol% followed by a steep increase at x > 7 mol%. This decrease could also be related to blocking effects induced by MIE that contributes to a reduction of space charge polarization. The anomalous decrease at x = 7 mol% coincided with a minimum of sigma(AC) for the same glass composition. Meanwhile, another nonlinear behaviour is observed on M ' with a maximum at x = 7 and 11 mol% which coincided with the location of sigma(AC) minimum that may be due to MIE effect attributed to the blocking effect of Bi2O3 to migrating ions which then led to high resistance. Electrical modulus analysis reveals the non-Debye relaxation nature for the glass samples indicating the presence of dynamic ions processes.