Study On Synthesis And Luminescent Properties Of LaPO₄: Eu³⁺ Luminescence Materials

Application of Rare-Earth luminescent materials, have attracted great attention owing to their excellent optical, electrical, and magnetic properties as a result of their unique electronic shell construction. Lanthanide nanophosphors have important applications in high-resolution displays, solid lasers and biological analysis. Establishing well-controlled synthetic strategies to these materials, understanding their growth and luminescent mechanism, and the relationships of their structures, morphologies and optical behaviors are crucial to the production of nanophosphors with designated Luminescent properties.In the first part, LaPO₄: Eu³⁺powders were synthesized by hydrothermal method. The phases, morphology and luminescent preperties of reaction products were investigated by XRD, SEM and FS, the effect of treatment temperatures thermal, reaction pH values, thermal treatment time on the luminescent preperties were investigated. The experiment showed that, the morphology of LaPO₄: Eu³⁺ was columnar-grained synthesized by La(NO₃)₃·6H₂O, Eu₂O₃ and Na₃PO₄·12H₂O at room temperature was amorphous. The milky colloidal solution of the LaPO₄: Eu³⁺ were treated by hydrothermal method. The product prepared at 120℃was well crystallized, all of the peaks could be well indexed to the hexagonal LaPO₄. The monoclinic phase structure was appeared with the temperature increase. All the powders were monoclinic phase structure when the temperature increase to 200℃. The samples has similar morphology at different temperatures that synthesised by hydrothermal method, although they had different phases. The pH value of reaction system has great effect on the morphology, the strong acidic environment (pH=1) of the mother liquor favors growth rates along one crystallographic plane and in the strong basic environment (pH=12) the product were particle with the size smaller than 100nm. Photoluminescence analysis shows that the product has great photoluminescence property, the excitation spectra of phosphors was shown the peaks of 392nm in the UV region, and emission spectra of phosphors was nearly at 588nm, The peak location of the charge transfer band (CTB) red-shifed in monoclinic structure.In the second part, the LaPO₄: Ce³⁺, Eu³⁺ powders were synthesized by hydrothermal method and calcination method. The morphology and phase structure has not change, when the Ce³⁺ doped LaPO₄:Eu³⁺. The luminous property of the products of the LaPO₄: Ce³⁺, Eu³⁺ weaked with the Ce³⁺ increase. The result showed that the peak location of the charge transfer band (CTB) blue-shifed, when the Ce³⁺ doped LaPO₄:Eu³⁺. The luminous property of the products weaked with the Ce³⁺increased, but the the peak location and the shapes had no change. The result indicating that the coordination environment of the Eu³⁺ is dependent on the Ce³⁺ but the lattice site of the Eu³⁺ has little effect.