The effects of silica additions (0.5-5 wt%) and sintering temperatures (980°C-1400°C) on the microstructure and photoluminescence (PL) of Ce-doped Y 3Al 5O 12 (YAG:Ce) phosphor ceramics were investigated in this study. Fourier transform infrared (FTIR) measurements showed the disappearance of silica (1 wt%) at 1200°C, indicating the incorporation of Si into YAG host and agreeing with the nuclear magnetic resonance (NMR) results. Microstructures of YAG:Ce ceramics with various silica additions observed using scanning electron microscope (SEM) and transmission electron microscope (TEM) revealed an obvious increasing densification and grain growth for the samples of >2.5 wt% silica at 1400°C. PL analysis demonstrated a higher intensity with increasing the sintering temperatures and the amount of silica addition. Two reasons were supposed to induce this PL enhancement of silica-treated YAG:Ce ceramics. First, Si will replace tetrahedral Al sites and induce a homogeneous diffusion as well as distribution of Ce dopant in the YAG host due to a smaller ionic radius of Si (0.026 nm) than that of Al (0.039 nm). Secondly, a liquid phase sintering will occur with the presence of silica in YAG:Ce, resulting in the densification of ceramics and an easier migration of Ce activators to inhibit the concentration quenching effect.
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