Synthesis Of Tungstates Luminescent Materials By Co-precipitation

In this paper, Eu³⁺,Dy3+,Sm³⁺doped Ca（Sr，Ba）WO₄nano-phosphors are synthesized bythe co-precipitation method. The morphology and composition of the powders werecharacterized by SEM and XRD.The phosphorescence of the powders was measured byspectrofluorimeter.The result show that the resulting material is MWO4（M=Ca, Sr., Ba） crystals whichhave a tetragonal system, belong to I4_1/a（88） space group of the scheelite structure. Thediffraction peaks moved towards smaller angle with increasing diameter of the metal cations.Doping different rare earth have a great influence on the luminescence. Eu³⁺-doped samplescan be excited by the near-UV （393nm）, the main emission peak at615nm, red fluorescence,the series of light-emitting powder may be used for manufacture white-LED excited bynear-ultraviolet chip. Sm³⁺-doped samples can also be excited by near-UV （403nm）excitation, red fluorescence, and compared with the Eu³⁺-doped samples, the luminousintensity is weak; doping of Dy³⁺can be excited by near-UV （351nm）, yellow fluorescence.The Eu³⁺doped Ca（Sr，Ba）WO4are synthesized after400℃,500℃600℃ignitionprocessing by the co-precipitation method. The nano-microspheres particles are synthesizedafter400℃ignition processing, they are100-300nm in diameter. The microspheres particlesare prepared after600℃ignition processing, they are about2-6um in diameter.;the ignitiontemperature also have some impact to the dispersion of tungstate samples.MWO4: Re³⁺（M=Ca, Ba, Sr）（Re=Sm, Eu and Dy） nano-phosphors are successfullyprepared at300℃for2h by molten salt-co-precipitation method. Compared with the ordinarysamples prepared by co-precipitation method, it reduce the reaction temperature.