Search

Femtosecond laser pulses were used to produce localized damage in the bulk and near the surface of baseline, Al[sub 2]O[sub 3]-doped and La[sub 2]O[sub 3]-doped sodium tellurite glasses. Single or multiple laser pulses were non-linearly absorbed in the focal volume by the glass, leading to permanent changes in the material in the focal volume. These changes were caused by an explosive expansion of the ionized material in the focal volume into the surrounding material, i.e. a microexplosion. The writing of simple structures (periodic array of voxels, as well as lines) was demonstrated. The regions of microexplosion and writing were subsequently characterized using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and atomic force microscopy (AFM). Fingerprints of microexplosions (concentric lines within the region and a concentric ring outside the region), due to the shock wave generated during microexplosions, were evident. In the case of the baseline glass, no chemistry change was observed within the region of the microexplosion. However, Al[sub 2]O[sub 3]-doped and La[sub 2]O[sub 3]-doped glasses showed depletion of the dopant from the edge to the center of the region of the microexplosions, indicating a chemistry gradient within the regions. Interrogation of the bulk- and lasertreated regions using micro-Raman spectroscopy revealed no structural change due to the microexplosions and writing within these glasses. [ABSTRACT FROM AUTHOR]

Abstract: Tellurite glasses have historically been shown to host large concentrations of halides. They are here considered for the first time as a waste form for immobilizing chloride wastes, such as may be generated in the proposed molten alkali salt electrochemical separations step in nuclear fuel reprocessing. Key properties of several tellurite glasses are determined to assess acceptability as a chloride waste form. TeO2 glasses with other oxides (PbO, Al2O3 +B2O3, WO3, P2O5, or ZnO) were fabricated with and without 10mass% of a simulated (non-radioactive) mixed alkali, alkaline-earth, and rare earth chloride waste. Measured chemical durability is compared for the glasses, as determined by the product consistency test (PCT), a common standardized chemical durability test often used to validate borosilicate glass waste forms. The glass with the most promise as a waste form is the TeO2–PbO system, as it offers good halide retention, a low sodium release (by PCT) comparable with high-level waste silicate glass waste forms, and a high storage density. [Copyright &y& Elsevier]