Exploring dielectric and AC conduction characteristics in elemental selenium glass modified with silver halides

Abstract

In this research work, we have examined the influence of silver halide doping on the dielectric dispersion and AC conduction of elemental selenium. The in-depth investigation shows that when the dopant silver halides are incorporated, there are noticeable changes in the parent selenium's dielectric constant (ε′), dielectric loss (ε′′), and AC conductivity (σ_ac). When we frame the discussion of the obtained results with the relevant transport models, we found that in pure selenium and Se₉₅(AgI)₅, conduction is primarily due to polaron hopping and follows the correlated barrier hopping (CBH) model. In contrast, Se₉₅(AgBr)₅ predominantly exhibits non-overlapping small polaron tunneling (NSPT). Interestingly, Se₉₅(AgCl)₅ demonstrates both NSPT and CBH conduction mechanisms, depending on the temperature range: NSPT is dominant between 303 K and 313 K, while CBH prevails from 318 K to 338 K. Additionally, our findings revealed the presence of both the Meyer–Neldel rule (MNR) and its reverse in the prepared silver halide chalcogenide alloys. The best optimization of dielectric constant and loss is observed for silver iodide as compared to silver chloride and silver bromide. Comparison with other silver-containing chalcogenide glasses indicates the better dielectric performance of the present silver halides containing selenium.