Development of Ytterbium-doped Optical Glasses and Glass-ceramics and Their Response to Various Treatments

This dissertation examines methods for modifying the properties of ytterbium-doped glasses through systematic studies of compositional variations and post- processing treatments. New oxyfluorophosphate glass compositions doped with ytterbium ions were developed and characterized to provide fundamental insights on structure-property relationships. Glasses in the NaPO₃-Na₂O system with varying fluorine concentrations were prepared and transparent glass-ceramics were obtained by controlled heat treatments. The effects of fluorine content and heat treatments on crystallization behavior and emission spectra were investigated. However, the resultant glasses suffered from hygroscopicity limiting their uses.

To address instability issues, the effects of incorporating aluminum oxide, titanium oxide, and zinc oxide on water absorption overtime was investigated. Results demonstrated that these network-forming oxides could successfully enhance water resistance without hindering the spectroscopic performances of the glass.es However, their crystallization tendencies were impacted. Nevertheless, this established compositional tailoring as an effective approach for strengthening glass connectivity and modifying properties.

Different glass families including phosphate, borosilicate, germanate and tellurite compositions doped with ytterbium were subjected to electron and proton radiation treatments. Their susceptibility to defects formation and their capacity for recovery in response to irradiation were evaluated and compared. Findings identified phosphates and borosilicates as exhibiting the highest initial radiation sensitivity but also greater self-recovery potential upon heat treatment. In contrast, tellurite glasses showed remarkably low defect creation during irradiation highlighting opportunities for radiation resistant materials.

Finally, ytterbium-doped borosilicate glass fibers fabricated with round and rectangular geometries were evaluated for stability in aqueous solution by monitoring the Yb³⁺ emission over time. Results elucidated the significant influence of fiber design on degradation kinetics, emphasizing that geometry is crucial for controlling resorption behavior tailored to biomedical applications.

Overall, this work advances fundamental understanding of manipulating Yb³⁺ doped glass-based material performance attributes through thermal, radiation, and compositional modifications. Insights into crystallization, hydrolytic stability improvement, radiation effects, and fiber geometry impacts supports optimization of emissive bandwidth, stability, tolerance, and dissolution profiles. Findings establishes design strategies and paves the way for further glass-based material progress with applications in photonics, healthcare, and beyond.