Topological transition and rigidity percolation in Ge–Se(S)–Cd glasses

Abstract

The glass-forming region in the Ge–Se–Cd system has been determined, where up to 12 at.% Cd can be introduced into the binary Ge 20Se 80 composition. Specific features in the compositional dependence of the density, d, and microhardness, H m, on the average coordination number, Z, have been found. In particular, two extrema have been observed at Z=2.4 and Z=2.68, both in bulk glasses and in amorphous films of the Ge x Se 98− x Cd 2 family, but the effects are less in the latter case. The same regularities have also been established for the glassy Ge–S–Cd system. The results obtained are compared with those for the previously studied Ge–Se–Fe system. They are discussed on the basis of rigidity percolation concepts and in terms of topological structural transitions in chalcogenide glasses.