Enhanced medium-range order in vapor-deposited germania glasses at elevated temperatures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Glasses are non-equilibrium solids whose properties depend heavily on preparation methods.
• Vapor-deposited molecular glasses allow tuning of structural organization via deposition parameters.
• Understanding amorphous oxide properties is key for advanced optical coatings.

Purpose of the Study:

• To investigate the modification of medium-range atomic structure in GeO2 glass via vapor deposition.
• To correlate structural changes with room-temperature internal friction.
• To identify microscopic origins of internal friction in amorphous oxides for improved interferometer coatings.

Main Methods:

• Vapor deposition of germanium dioxide (GeO2) glass at varying substrate temperatures.
• Raman spectroscopy to analyze atomic structure, specifically the population of GeO4 rings.
• Comparison of vapor deposition near the glass transition temperature with post-growth annealing.

Main Results:

• Elevated substrate temperatures during vapor deposition modify the medium-range atomic arrangement (<2 nm) of GeO2 glass.
• Increased substrate temperatures lead to a higher population of six-membered GeO4 rings, confirmed by Raman spectroscopy.
• Deposition near the glass transition temperature is more effective than annealing for altering medium-range structure.

Conclusions:

• Enhanced medium-range organization in vapor-deposited GeO2 glass correlates with reduced room-temperature internal friction.
• The study identifies a key factor influencing internal friction in amorphous oxides.
• Findings are critical for designing next-generation interference coatings for gravitational wave interferometers.