Preparation And Luminescent Properties Of Composited Tungstate-molybdates Microcrystallines Containing Rare Earth Metals

Scheelite-type tungstates and molybdates have scheelite structure belonging tetragonal(A=Ca,Sr,Ba;B=Mo,W), which are the typical self-activated luminescent material,In the UV and X-ray excitation of fluorescence can be rendered efficient. Besides, it can carry out the change of the optical performance and get a new generation of fluorescent materials with doping rare earth ions.In this article, Li4-3x Ax(BO4) 2(A = Eu or Sm, B = Mo or W,0≤x≤4/3) and Li2.8A0.4(WO4)2-x(Mo O4)x(A = Eu or Sm,0 ≤ x ≤ 2.0) microcrystallines were synthesized by hydrothermal method and solid state reaction method, The ceramics structure, surface morphology and optical properties of the as-synthesized microcrystallines were used of X-ray apparatus(XRD), scanning electron micrograph(SEM) and fluorescence analyzer(FL).(1)A series of Li4-3x Ax(BO4)2(A=Eu or Sm,B=W or Mo) microcrystallines have been synthesized. The influence of the ratio of rare earth ions to alkali metal ions Li+ with different x-component of the crystal properties have been discussed in detail. The faction which affect the luminescent properties, such as doping concentration rare earth ions by hydrothermal method and such as the effect of sintering temperature,holding time and concentration of rare earth ions by optimizing process, The results reveal that:①All the obtained Li4-3x Ax(BO4)2(A= Sm or Eu,B= Mo or W) microcrystallines all are typical scheelite structure with tetragonal symmetry.②Among the RE ions, the Eu3+ion is an Activator, The excitation and emission wavelength show that these phosphors can be effectively excited by ultraviolet(395 nm)light, emitting the maxium line at 614 nm with pure red light. Another Sm3+ as activator, it can be effectively excited by the ultraviolet(450 nm) light, the maxium line at 563 nm with pure green light. The absorptions at 395 nm and 450 nm are nicely fitting in the emission wavelengths of ultraviolet or blue LED chips. So the system of red and green phosphors are candidates for solid-state lighting applications.③The properties of this phosphor were improved using charge compensation, The rare earth ions of each emission peaks were clearly appeared in all of the microcrystallines, and realize the emission peak intensity of regulation.④Results shou that hydrothermal method prefers the solid state reaction method in this system.(2)A Synthesized a series of Li2.8A0.4(WO4)2-x(Mo O4)x(A=Eu or Sm) microcrystallines were synthesized, then discussing the influence of the microcrystalline structure,morphology and optical properties. Our results reveal that:①All the Li2.8A0.4(WO4)2-x(Mo O4)x(A=Eu or Sm) microcrystallines are well crystalized,and were single-phase scheelite structure with tetragonal symmetry.②All the microcrystallines of Li2.8Eu0.4(WO4)2-x(Mo O4)x by hydrothermal method and solid state reaction method coordinates are in the red zone. The color is more pure when x=1.4. Fluorescence analysis results reveal that the transitions of5D0→7F0 of Eu3+ion(located at 580nm) occupies a sites of symmetrical obviously. All the microcrystallines of Li2.8Sm0.4(WO4)2-x(Mo O4)x obtained by hydrothermal method and solid state reaction method coordinates are in the green zone. given the best colr purity at x=1.6.③Results shou that hydrothermal method prefers the solid state reaction method in this system.