Optical and crystal growth studies of ZnO-Bi2O3-B2O3 glass

Transparent ZnO-Bi2O3-B2O3 (ZBB) glasses were prepared using the melt quench technique. Various compositions of the glass containing stoichiometric ratios of Zn/Bi/B as well as some including As2O3 for redox control and LiNO3 for use as nucleation species, were studied. ZBB glass-ceramics containing nanocrystallites have a potential for use as low-cost UV-MWIR optical devices such as microlenses, waveguides, and photonic crystals. Our goal was to exploit crystal growth in the ZBB systems by heat treatment in order to obtain transparent glass-ceramics that contain homogenous volume crystallization. Thermal behavior was studied using differential scanning calorimeter (DSC) measurements. Physical and optical characterizations included Raman spectroscopy to identify molecular connectivity, energy-dispersive X-ray spectroscopy (EDX) for elemental analysis, VIS/NIR transmission and reflection spectroscopy for optical bandgap and IR transmissivity, X-ray diffraction (XRD) to determine crystal phase, and transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED) to quantify size, number density, and identification of nanometer sized secondary phases. Heat treatments were used to nucleate and grow BiB3O6 and Bi2ZnB2O7 nanocrystals in ZBB. We explored new compositions within the ZBB system and heat treatment techniques to assess the transformation of the amorphous glass phase into the crystalline phase. In-situ XRD and TEM imaging was employed to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase. BiB3O6, Bi2ZnB2O7, and ZnO was found to grow on the surface of some compositions. Compositions and heat treatment procedures were developed to facilitate volume crystallization and reduce unwanted surface crystallization.