The vacuum ultraviolet PL and PLE spectra and chromaticity characteristics for the synthesized phosphors were measured and compared against those of a commercial red-emitting phosphor. The optimal substitution proportions of P for V and Gd for Y were determined to be 60 and 20 mol %, respectively, for (Y0.95-yGdy)(V1-zPz)O4 doped with 5 mol % Eu3+. YVO4:Eu3+-based phosphors in three series with compositions (Y1-圎ux)(V1-zPz)O4, (Y0.95-yGdyEu0.05)(V0.4P0.6)O4 and (Y0.95-yEu0.05Gdy)(V1-zPz)O4 were synthesized and investigated as potential red-emitting phosphors for a plasma display panel (PDP). Experimental results show that YVO4: Ce3+ crystal is a potential blue-emitting material for white-emitting LED under ultraviolet excitation. In YVO4: Ce3+ crystal, the wave functions of Ce3+ overlaps effectively to the π orbital of VO43-, via this interaction the energy can be transfer effectively from VO43- to Ce3+, so that the blue-emitting intensity of Ce3+ is improved significantly. YVO4 and YVO4:Ce3+ single crystals radiate a wideband blue light centered at 440 nm when excited by 325 nm ultraviolet light, the former corresponds to 3T2→1A1 and 3T1→1A1 transition of VO43-, while the latter corresponds to 5d→4f transition of Ce3+. The excitation spectra of YVO4 and YVO4:Ce3+ crystals are both in the range from 260 nm to 360 nm, due to the charge transfer transition of the O2-V5+ ion pairs of VO43- polyhedron. The X-ray photoelectron spectroscopy (XPS) shows that the Ce (3d) peak splits into five peaks located at 882.0, 885.8, 902.9, 908.0 and 915.9 eV, which indicates that the Ce3+ and Ce4+ ions coexist in both kind of samples. XRD pattern shows that Ce3+ ion enters the YVO4 lattice by occupying the Y3+ sites and the YVO4 crystal structure change little by the addition of Ce ions. YVO4 and YVO4:Ce3+ single crystals doped with 2.0at% CeO2 (or Ce2(CO3)3) were grown by using the Czochralski method. On base of the calculated result, the relationship between the electron transition and the luminance is illustrated. Furthermore, the first principle calculation is used to calculate the band-structure of the YVO 4 and YPO 4 crystals. The photoluminescence spectra show that the luminous efficiency of YVO 4:Eu 4 core-shell phosphor is 66.75% higher than that of YVO 4:Eu 3+ phosphor, which also has high color purity. ![]() The core-shell phosphor with diameter of 10-30 nm and shell thickness of 5-10 nm, regular crystalline morphologies, highly uniform in size and distribution, high degree of crystallinity. The XRD and TEM results indicate that the synthetic products are composed of the YVO 4:Eu 3+ core and YPO 4 shell. X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence spectra were used to characterize the feature of YVO 4:Eu 4 core-shell phosphor. In order to improve the stability and luminous efficiency of YVO 4:Eu 3+ phosphor, YVO 4:Eu 4 nano core-shell phosphor was prepared by using hydrothermal method.
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