Thermal and electrical switching studies on Ge 20Se 80 − xBi x (1 ≤ x ≤ 13) ternary chalcogenide glassy system

Abstract

Alternating Differential Scanning Calorimetric (ADSC) and electrical switching studies have been undertaken on Ge 20Se 80 − xBi x 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 (T g), crystallization temperature (T c1) and thermal stability (∆T) of Ge 20Se 80 − xBi x 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 T g, T c1, ∆T, ∆C p and ∆H NR, at the composition x = 10, which indicates the occurrence of chemical threshold in these glasses at this composition. Electrical switching studies indicate that Ge 20Se 80 − xBi x 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 V T around x = 6, which is related to bismuth phase percolation at higher concentrations of Bi.