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

Area of Science:

• Materials Science
• Solid State Chemistry
• Amorphous Materials

Background:

• Arsenic sulfide glasses are technologically important materials.
• Understanding the local atomic structure of ternary glasses is crucial for tailoring their properties.
• The role of silver (Ag) in modifying the structure of arsenic(2)sulfide(3) (As(2)S(3)) glasses requires detailed investigation.

Purpose of the Study:

• To elucidate the structural evolution of (As(0.4)S(0.6))(100-x)Ag(x) glasses with varying silver content.
• To determine the preferred bonding sites and coordination numbers of constituent atoms (As, S, Ag).
• To analyze the impact of silver incorporation on the network structure and bond formation.

Main Methods:

• High-energy X-ray diffraction and neutron diffraction were employed to probe atomic arrangements.
• Extended X-ray absorption spectroscopy (XAS) at As and Ag K-edges provided site-specific information.
• Reverse Monte Carlo (RMC) simulations were used to model experimental data and derive structural parameters.

Main Results:

• Silver preferentially bonds with sulfur, forming Ag-S bonds in the As(2)S(3)-Ag ternary glasses.
• The addition of Ag leads to an increase in the formation of homoatomic As-As bonds.
• Direct Ag-Ag bonds were observed only in the glass with the highest Ag content (12 at.%).

Conclusions:

• Silver acts as a network modifier, disrupting the As-S network and promoting As-As bond formation.
• The coordination numbers of As (≈3) and S (≈2) remain relatively constant, similar to binary As(2)S(3) glass.
• The first sharp diffraction peak is attributed to As-As and As-S correlations, characteristic of the amorphous structure.