Influence of Ag Doping on Physico-Chemical Properties of the Ge28Sb12Se60 Chalcogenide Glassy Matrix

Abstract

Thermal, optical and electrical properties of the Ag x (Ge 28 Sb 12 Se 60) 100x system (for x = 0 to 20) are systematically studied using various characterization techniques. In the present study, we have shown the reproducibility of the current results with the previously published literature and several novel results are also presented. The impedance data for the understanding of electrical properties of the materials has been analyzed using the random-walk (RW) model. We observed that, Ag playing two different concentration dependent roles i.e. above and below the 5% of Ag concentration, which is confirmed by the Raman analysis. The anomalous behaviors of electrical conductivity, optical and thermal properties with increasing Ag concentrations are explained by the role of Ag in the structural modification. We compared the diffusion coefficient (D), obtained from the RW model analysis with the experimental data(obtained from tracer diffusion) and found diffusion coefficient (D), obtained from the RW model are in good agreement corresponded with the experimental values. We also found a major change in conductivity of insulating Ge 28 Sb 12 Se 60 (~ 10-14 S·cm-1) to a fast ionic conductor for Ag 15 (Ge 28 Sb 12 Se 60) 85 (~ 10-6 S·cm-1), i.e., a nine orders of magnitude. We demonstrated that the random-walk model can replacea time consuming and expensive tracer diffusion method for the determination of D. The present article helps to understand the ion conduction mechanism in disordered / amorphous materials.