Highly transparent, bright green, sol-gel-derived monolithic silica-(Tb,Ce)PO sub(4) glass-ceramic phosphors

Monolithic silica glasses containing TbPO sub(4) nanocrystals with narrow size distribution and exhibiting excellent ultraviolet (UV) transparency have been prepared using a cosolvent-free sol-gel method. Despite the high refractive index of TbPO sub(4) crystals ( similar to 1.8), observed Rayleigh scattering from the crystals is negligible because of the small average crystal size ( similar to 5 nm). The precipitated crystals are of the metastable monoclinic form, different from the stable tetragonal form. The glasses are UV photoluminescent, even at stoichiometric Tb composition, and doping with a small amount of Ce super(3+) ions increased the external quantum efficiency to similar to 0.76 under excitation at 290 nm. Unlike conventional glassy phosphors, the photoluminescence efficiency is high despite the high SiOH concentration of the glass matrix because of confinement of RE ions to the crystal phase.