Colloid Formation in As2O3-Doped Gallium Silicate Glasses

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New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Colloid formation in As2O3-doped alkali galliosilicate glass was studied via reduction of Ga and As in a galliosilicate glass matrix. The colloids were formed by heat treatment of the glasses in a hydrogen H2 or deuterium D2 atmosphere. The heattreatment temperature and duration were varied in optimizing the nucleation and growth processes. X-ray diffraction (XRD), differential scanning calorimetry (DSC), ultravioletvisible- near infrared (UV-Vis-NIR), and Fourier transform infrared (FTIR) spectroscopies were used to study the kinetics and dynamics of the processes. Hydroxyl ion formation in these glasses was correlated to the formation of colloids of Ga or As or some combinations of thereof. Colloid formation was supported by environmental scanning electron microscopy (SEM) and energy dispersion spectrometer (EDS). Absorbance versus (1/λ4), (1/nm4) plots suggested Rayleigh scattering, though quantum size effects could not be experimentally verified. Square root dependence of heattreatment time on the change in IR absorbance suggested a diffusion-controlled process. Spectroscopic evidence showed increasing hydroxyl concentration with treatment time in hydrogen atmosphere, while hydroxyl concentration decreased in deuterium atmosphere due to the removal of pre-existing hydroxyl and isotope exchange.
Advisory committee members: Alexis Clare, Matthew Hall. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Material Science and Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University