Atomic structure of As(2)S(3)-Ag chalcogenide glasses

(As(0.4)S(0.6))(100-x)Ag(x) glasses (x = 0, 4, 8, 12 at.%) have been studied with high-energy x-ray diffraction, neutron diffraction and extended x-ray absorption spectroscopy at As and Ag K-edges. The experimental data were modelled simultaneously with the reverse Monte Carlo simulation method. Analysis of the partial pair correlation functions and coordination numbers extracted from the model atomic configurations revealed that silver preferentially bonds to sulfur in the As(2)S(3)-Ag ternary glasses, which results in the formation of homoatomic As-As bonds. Upon the addition of Ag, a small proportion of Ag-As bonds (N(AgAs)≈0.3) are formed in all three ternary compositions, while the direct Ag-Ag bonds (N(AgAg)≈ 0.4) appear only in the glass with the highest Ag content (12 at.%). Similar to the g- As(2)S(3) binary, the mean coordination number of arsenic is close to three, and that of sulfur is close to two, in the As(2)S(3)-Ag ternary glasses. The first sharp diffraction peak on the total structure factors of As(2)S(3) binary and (As(0.4)S(0.6))(100-x)Ag(x) ternary glasses is related to the As-As and As-S correlations.