Preparation and Properties of Yttrium-Silicon-Aluminum Oxynitride Glasses

Glasses containing up to 7 at.% nitrogen were prepared in the system Y-Si-Al-O-N. The glass transition temperature, hardness, and relative fracture toughness increase and the thermal expansion coefficient decreases with increasing nitrogen content. Weight losses after 350 h in 95°C distilled water are not simply related to nitrogen content, but for some compositions they are half that reported for fused silica. The electrical conductivity at 548°C and 10 kHz is 7.8×10⁻¹⁰ (Ω·cm)⁻¹ for one composition. Fourier transform ir spectroscopic analysis indicates the presence of Si-N bonds in the glasses. The data suggest that nitrogen substitutes for oxygen in the glass network to produce a more highly cross-linked structure.