Preparation And Properties Of Rare Earth Phosphors For Energy Saving Lighting

Rare earth phosphors play an important role in energy-saving lighting. To meet the demand of rare earth luminescent materials, several rare earth phosphors for lighting were synthesized and their properties were investigated, including:Tb3+and Ce3+co-activated LiZnP04phosphors with high luminescence efficiency were synthesized by a high temperature solid-state reaction at1000℃for3h. The XRD patterns, photoluminescence spectra and SEM were recorded and the effects of Tb3+and Ce3+concentration, sintering condition on the luminescent properties of as-synthesized phosphors were investigated. The emission spectra under ultraviolet (200-300nm) radiation showed a dominant peak at543nm attributed to the5D4â†'7F5transition of Tb3+, which was greatly enhanced by the co-doping of Ce3+, indicating that there occurred an efficient non-radiative energy transfer from Ce3+to Tb3+. The optimal doping concentrations of Tb3+and Ce3+were determined to be9%and10%, respectively. Meanwhile, Eu3+or Tb3+doped bismuth phosphate phosphors have been synthesized at a relative low temperature between800and900℃. The obtained phosphors possess pure monoclinic phase structure and regular morphology. The as-synthesized Eu3+doped bismuth phosphate orange red phosphor shows spherical particles with size ranging from1to2micrometer. While the Tb3+doped bismuth phosphate green phosphor displays uniform square morphology.The synthesis method of YAG:Ce was modified by adding some latent solvents in the reaction process to improve the luminous efficiency and dispersion property. The obtained phosphors have spherical morphology and show higher luminescent strength than that of commercial product. At the same time, Ca2Si5N8:Eu red phosphors were synthesized at relative low temperature and atmospheric pressure by employing active silicon as raw material. The effect of synthesis conditions on the phase purity and luminescent property are investigated. It is found that crystalline silicon with a slight lower stoichiometry is beneficial to the synthesis of Ca2Si5N8:Eu red phosphor with high luminescent efficiency and pure phase. The emission peak of obtained phosphors under the excitation of460nm light is a wide band with maximum at630nm corresponding to the emission of Eu2+.