Synthesis And Optical Properties Of Ba₃（PO₄）:Eu³⁺ Red Phosphors For White LED

The synthesis and properties of phosphors used for white LEDs were paid moreattention with the extension of applied field and the development of preparationtechnology in white LEDs. Especially, the properties of red phosphor excited by blueand UV light can affect directly the color rendering of white LEDs. However, redphosphors have some defects and shortcomings. Furthermore, the red phosphors havebecome the bottle-neck for the white LEDs development. Nowadays, with the rapiddevelopment, the global demand for the white LEDs increasing, it’s necessary to finda new type of red phosphors for white LED.A series of red phosphors Ba3(PO4)2:Eu3+were prepared by solid state reactionmethod. The properties of Ba3(PO4)2:Eu3+phosphor were improved using chargecompensation (Li+、Na+、K+) and the flux BaF2. The structure, morphology andcomposition of the phosphor were tested by XRD, SEM and IR. The thermal stabilitywas analyzed by TG and DSC. The luminescence properties were analyzed byphotoluminescence excitation and emission spectra, the decay and the colorcoordinates. The findings are as following:XRD results demonstrate that Ba3-x(PO4)2:xEu3+，Ba2.92(PO4)2:0.04Eu3+，0.04R+（R=Li、Na、K），Ba3(PO4)2:0.04Eu3+，xBaF2phosphors were prepared. Meanwhile,Two matrix Ba3Eu(PO4)3and Ba10F2(PO4)6were found obviously. SEM resultsindicate that the phosphors should be composed of2.5μm3volume particles. Thermalanalysis show that Ba3(PO4)2crystals is formed at about600℃. The excitationspectrum can be divided into two regions. The broad absorption band centered at262nm is assigned to the charge transfer transitions of Eu-O, and other excitation peaksare assigned to the f-f transitions of Eu3+.The emission spectra consist of peakscentered in578nm,593nm,613nm,653nm regions, assigning to the5D0�'7F0，5D0�'7F1，5D0�'7F2，5D0�'7F3transitions of Eu3+respectively. The charge compensation (Li+, Na+, K) and the flux BaF2can enhance the luminescent intensitiesof Ba3(PO4)2: Eu3+phosphors. The CIE chromaticity coordinates of Ba3(PO4)2: Eu3+phosphors locate at (0.640.35) under the excitation of393nm. The fluorescencelifetime is about2.3ms. It is indicated that Ba3(PO4)2: Eu3+phosphors might be apromising red phosphor for white LEDs excited by n-UV light.