Short range order and Ag diffusion threshold in Agx(Ge0.25Se0.75)100 x glasses

International audienceA structural investigation of Agx(Ge0.25Se0.75)100 x glasses with x¼5, 15, and 25 at.% has been carried out by neutron diffraction and ab initio molecular dynamics (AIMD) simulation. A structural model for the glasses has been proposed: the Ge(Se1/2)4 tetrahedra would remain the fundamental structural units in all samples. The introduction of Ag in the Ge0.25Se0.75 network would lead to a decrease in homopolar Se-Se bonds and appearance of Ge-Ge bonds. A strong evolution in the Ag-Ag correlations upon introduction ofAg was observed with the Ag-Ag correlation distances changing from 4.4A for the Ag-poor glass to 3.0A for the Ag-rich ones. Such information was used to discuss the evolution of conductivity with Ag content in these glasses