Enhanced Emission of Eu3+ in Boron Ions-Doped Sol-Gel SiO2 Phosphors

Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu 3+ ions are, which are due to the transitions of 5D0→7FJ（J=0, 1, 2, 3, 4） of Eu 3+ , respectively. The transition of 5D0→7F1 is split into two peaks. When B is introduced to the Eu-doped samples, the red Eu 3+ emission is enhanced remarkably. This is mainly associated with the formation of Si-O-B bonds in the luminescent materials and the lowering of network symmetry. When the sample heated up to 850 ℃ was excited at 350 nm, strong blue Eu 2+ emission band centered at 437 nm is observed for Al-doped silica xerogel. Compared with Al-doped sample, the blue emission center of B, Al co-doped sample shifts to 425 nm and the intensity becomes weaker. This is due to the modification of network structure by the addition of B ions.