YF3-Regulated Crystallization and Stability in Gallate Glasses

Gallate glasses hold significant promise for mid-infrared optical applications because of their low phonon energies and broad infrared transmission windows. However, the Ga 2 O 3 –CaO binary system suffers from poor glass-forming ability and high melting temperatures, making it difficult to obtain stable bulk glasses. In this study, YF 3 -regulated 32Ga 2 O 3 -(68- x )CaO- x YF 3 ( x = 0–10 mol%) gallate glasses were synthesized and investigated. The amount of bridging oxygen in the glass network decreases continuously with increase in the YF 3 content. Meanwhile, the glass stability first increases and then decreases. The glass achieves the best stability ( ΔT = 138°C, S = 5.71, H r = 0.474) when the YF 3 content is 8 mol% (GY8). The non-isothermal crystallization kinetics of the GY8 glass were studied based on the classical Johnson–Mehl–Avrami theory. The crystallization activation energies calculated by the Kissinger, Ozawa, and Augis–Bennett equations are in good agreement with each other, and the Avrami exponent calculated by the Matusita–Sakka and Augis–Bennett equations is approximately 3, indicating that the crystallization mechanism of the GY8 glass is either volume nucleation with two-dimensional growth, or three-dimensional growth from a fixed number of pre-existing nuclei. This system guides the design of glass composition and process optimization, thereby providing a theoretical foundation for the preparation of large-sized, highly stable glasses.