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

Mixed ionic-electronic 98[20Li 2 O- x Bi 2 O 3 -(80- x )TeO 2 ]-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 Bi 2 O 3 showed an initial increase in σ 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 Bi 2 O 3 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 σ 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 σ AC minimum that may be due to MIE effect attributed to the blocking effect of Bi 2 O 3 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.