Micron-Nanometer Rare Earth Vanadate Phosphors By In-situ Construction Of Hybrid Precursors

In this paper, we put forward a novel optimized synthesis of rare earth vanadates through in-situ chemical precipitation reactions. Among rare earth coordination polymers with aromatic carboxylic acids was used as the precursors of rare earth oxide components, and polyethylene glycol (PEG) and ammonium vanadate (NH₄VO₃) were composed to assemble inorganic/organic hybrid polymeric dispersing media by an in-situ chemical co-precipitation process. After the heat-treatment of the resulting multicomponent hybrid precursors, the rare earth vanadate phosphors were achieved. Most of the particles exhibit good crystal morphology and the size of the particles is in the range of micrometer or sub-micrometer.The three-dimensional sizes of crystalline grain are rather thick to afford high power, it needs to refer that the crystalline powder and micrometer dimension for these powders with high strength would be very useful for the application to obtain high efficient phosphors because these micro crystalline materials can result in the high luminescent intensities which can avoid the traps formation of excess surface area for nanometer phosphors.Four series of luminescence materials have been successfully synthesized by assembling hybrid precursor co-precipitation technology, which are LnVO₄: RE (Ln = Y, Lu; RE =Eu³⁺, Dy³⁺, Sm³⁺, Er³⁺); Y_xGd_1-xVO₄:RE and LnP_xV_1-xO₄: RE (including Y_xGd_1-xVO₄:Eu³⁺, Y_xGd_1-xVO₄:Tm³⁺, YP_xV_1-xO₄: Dy³⁺, YP_XV_1-xO₄: Eu³⁺, GdP_xV_1-xO₄: Dy³⁺ LaP_xV_1-xO₄: Dy³⁺); alkali metals and alkaline-earth metals doped vanadate phosphors (Y_0.48Dy_0.02Li_1.5VO₄, M₃Ln(VO₄)₃:RE (M = Ca, Sr, Ba; Ln = Y, Gd; RE = Eu³⁺, Dy³⁺, Er³⁺) and Pb²⁺, Bi³⁺ sensitized rare earth vanadate luminescent materials (YVO₄: Pb²⁺, Bi_xY_1-xVO₄: Eu³⁺, Bi_xY_1-xVO₄:Dy³⁺, Bi_xY_1-xVO₄:Er³⁺ ). All the phosphors exhibit the characteristic fluorescence of rare earth ions and the systems doped with different concentration of rare earth ions appear the concentration quenching phenomenon. As for the system of LnP_xV_1-xO₄: Dy³⁺, we find that the intensity ration of yellow-to-blue (Y/B) of Dy³⁺ was significantly influenced by the x value, which is that with the x value increasing, the Y/B intensity ration decreased. Besides this, Pb²⁺ and Bi³⁺ are both excellent sensitizers in the system of rare earth vanadates and efficient energy transfer can appear from Pb²⁺, Bi³⁺ to rare earth ions.