Tailoring of dielectric behavior and a.c. conduction in binary Se80Te20 glass by incorporation of transition metals (Fe, Co, Ni, Cu)

Abstract

Transition metals (TMs) iron, cobalt, copper, and nickel have been chosen as the chemical modifiers with a binary alloy Se80Te20 as the parent sample to make novel Se78Te20TM2 (TM = Fe, Co, Ni, Cu) alloys. The frequency dependence of dielectric loss and a.c. conductivity (σac) have been studied and the possible mechanism has been checked. The dielectric constant (ε') shows significant variation among the samples, with the parent Se80Te20 alloy exhibiting the highest value, followed closely by Se78Te20Cu2. Conversely, Se78Te20Fe2 and Se78Te20Ni2 alloys exhibit much lower values. The dielectric loss also varies widely, with Se80Te20, while Se78Te20Fe2 and Se78Te20Ni2 alloys present extremely low values of loss. The barrier height ranges between 0.31 eV (Fe-doped sample) and 1.2 eV (Ni-doped sample), indicating that doping influences the band gap significantly. The hooping distance shows considerable differences, with Fe-doped alloys exhibiting the highest value at 39.5 Å, while Co-doped samples show the lowest at 11.4 Å. Applicability of the Meyer-Neldel rule is observed in the a.c. conduction for all samples. The reducing nature of the power-law exponent “s” with increasing temperature indicates the correlated barrier hopping model for Se80Te20 and Se78Te20TM2 (TM = Co, Ni, Cu) alloys, as they exhibit a certain nature of variation. However, because “s” increases with temperature, the non-overlapping small polaron tunneling model is a particularly appropriate mechanism for a.c. conduction of ternary Se78Te20Fe2 alloy. Furthermore, we estimated the density of localized states for the synthesized material at various temperatures. The maximum reduction in the density of states is observed for the iron-containing parent sample. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.