Thermal and electrical switching studies on Ge20Se80 − xBix (1 ≤ x ≤ 13) ternary chalcogenide glassy system

Alternating Differential Scanning Calorimetric (ADSC) and electrical switching studies have been undertaken on Ge20Se80 − xBix glasses (1 ≤ x ≤ 13), to understand the effect of topological thresholds on thermal properties and electrical switching behavior.It is found that the compositional dependence of glass transition temperature (Tg), crystallization temperature (Tc1) and thermal stability (∆T) of Ge20Se80 − xBix glasses show anomalies at a composition x = 5, the rigidity percolation/stiffness threshold of the system. Further, unusual variations are also observed in different thermal properties, such as Tg, Tc1, ∆T, ∆Cp and ∆HNR, at the composition x = 10, which indicates the occurrence of chemical threshold in these glasses at this composition.Electrical switching studies indicate that Ge20Se80 − xBix glasses with 5 ≤ x ≤ 11 exhibit threshold switching behavior and those with x = 12 and 13 show memory switching. A sharp decrease has been noticed in the switching voltages with bismuth concentration, which is due to the more metallic nature of bismuth and the presence of Bi+ ions. Further, a saturation is seen in the decrease in VT around x = 6, which is related to bismuth phase percolation at higher concentrations of Bi.