A.C. conduction in glassy alloys of Se₉₀Sb_10-xAg_x

Temperature and frequency dependence of a.c. conductivity is studied in glassy Se₉₀Sb_10-xAg_x (x=2, 4, 6 and 8) in the temperature range (288–358 K) and frequency range (1–500 kHz). An agreement between experimental and theoretical results suggests that the behavior of glassy Se–Sb–Ag system can be successfully explained by correlated barrier hopping (CBH) model. The results show that bipolaron hopping dominates over single polaron hopping in present case, which is explained in terms of lower value of potential barrier. By fitting the experimental data to CBH model, the density of charged defect states is calculated for all the glasses studied. The composition dependence of the density of these states is studied and found to show a maxima at 6 at% of Ag which is explained in terms of the mechanically stabilized structure at a particular average co-ordination number.