Effect of phase separation on crystallization of glasses in the BaO-TiO2-SiO2 system

Abstract

The effects of phase separation on the crystallization behavior of glasses were investigated in order to materialize a high-luminous glass-ceramic phosphor, which consists of fine phosphor crystals and a transparent glass matrix prepared due to phase separation. The glass ceramics in BaO-TiO2-SiO2 has the potential to show high photoluminescence intensity, because of multiple light scattering at the boundary between the phosphor crystal and the glass matrix. The crystallization behaviors of the glasses were examined using both the XRD analyses for an isothermal heat treatment process and the DTA measurements as a non-isothermal treatment process. The phase-separation in the glass significantly affected the subsequent crystallization behavior. In the non-phase-separated glasses, surface crystallization occurred first, and crystallization then proceeded inside the glasses. In the phase-separated glasses, the crystallization was considered to start at the boundary of two glass phases inside the glass and the crystals grew in BaO-TiO2-rich phases. This apparent bulk crystallization owing to the phase separation has the potential to materialize a high-performance phosphor composite.