Optical Properties and Structure of As-Sb Chalcohalide Glasses by Raman Scattering and Density Functional Theory...

Area of Science:

• Materials Science
• Solid State Chemistry
• Optoelectronics

Background:

• Chalcogenide glasses are crucial for optical applications.
• Understanding structure-property relationships in ternary glasses like Sb-As-S-I is essential for material design.

Purpose of the Study:

• To investigate the impact of antimony content on the optical properties, structure, and vibrational modes of SbAs_37-S₄₈I₁₅ glasses.
• To elucidate the local atomic structure and bonding characteristics within these ternary glasses.

Main Methods:

• Synthesis and characterization of SbAs_37-S₄₈I₁₅ glasses with varying antimony content (0-37 at. %).
• Measurement and analysis of optical properties (refractive index, absorption coefficient, optical band gap).
• Off-resonant Raman spectroscopy combined with Density Functional Theory (DFT) calculations for structural and vibrational analysis.

Main Results:

• Optical parameters (refractive index, absorption coefficient, optical band gap) showed a near-linear dependence on antimony content.
• Raman spectra analysis, supported by DFT calculations, indicated statistical mixing of iodine atoms within pyramidal units.
• Evidence suggests iodine preferentially replaces sulfur in antimony-based pyramids over arsenic-based ones.

Conclusions:

• The study establishes a clear correlation between antimony concentration and the optical characteristics of SbAs_37-S₄₈I₁₅ glasses.
• The findings support a statistical site occupancy model for iodine, challenging models of isolated AsI₃/SbI₃ molecules.
• Antimony-based structural units are more likely to incorporate iodine and form corner-sharing configurations in these mixed glasses.