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Synthesis and Spectral Characteristics of Eu3+ and Tb3+ Doped MMoO4 （M=Ca, Zn, Ba） Phosphors

Author: XuChengKe
Tutor: QiuGuiMing
School: Shantou University
Course: Materials Physics and Chemistry
Keywords: CaMoO4: Eu3 ZnMoO4: Tb3 BaMoO4: Eu3 White LED Spectral characteristics Phosphor
CLC: O482.31
Type: Master's thesis
Year: 2010
Downloads: 173
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Abstract


White LED with traditional lighting incomparable superiority, its application and development of more and more people to pay attention, is called a new generation of green lighting. Therefore applied to white LED phosphor preparation and spectral properties of concern. In this paper, high-temperature solid-phase synthesis of CaMoO 4 : Eu 3 red phosphor, ZnMoO 4 : Tb 3 green phosphor and BaMoO 4 : Eu 3 red phosphor, and the crystal structure of the samples, the spectral characteristics were studied. In CaMoO 4 matrix doped with Eu 3 ions, prepared a highly efficient red luminescent material. Study found, Eu 3 ions in the CaMoO 4 lattice occupy Ca 2 ions Sites of; Ca1-xEuxMoO 4 excitation spectrum consists of a broadband peaks and multiple spikes composed broadband in 220 ~ 320nm range, strong two peaks located at 394nm and 464nm; through the sample spectra for further analysis, the sample is considered to be attributable to broadband excitation in Mo6-O2-charge transfer absorption, does not belong to Eu 3 -O2-charge transfer transitions. The emission spectra of the samples and the Eu 3 doping concentration on the luminescence intensity. High temperature solid phase prepared ZnMoO 4 : Tb 3 green phosphor, the samples were characterized by X-ray diffraction (XRD) and fluorescence spectroscopy. XRD results showed that the sample can be obtained at 800 ℃ single ZnMoO 4 phase. Broadband excitation spectrum consists of a number of peaks and spikes composed broadband belong Mo6-O2-charge transfer absorption band (CT), and found that broadband peak position with Tb 3 doping concentration increases a blue shift , spikes belonging Tb 3 of 4f-4f transitions, the strongest excitation peak at 377nm Department. Peak emission spectrum consists of four components, the strongest emission peak at 543nm office, corresponding to Tb 3 of the 5D4-7F5 transition, belonging to the magnetic dipole transition. Studied ZnMoO 4 : Tb 3 phosphors main emission peak at 543nm intensity Tb 3 doping concentration changes. The results show that with Tb 3 concentration, the emission intensity of the first peak increases; when Tb 3 concentration of x = 0.15, the peak maximum intensity; then with Tb 3 concentration increased, the peak intensity decreases. Fluorescence lifetime test to get Tb 3 of the 5D4-7F5 transition emission fluorescence lifetime value of 0.506ms. Studies show that the spectral characteristics, ZnMoO 4 : Tb 3 is a possible application in green color on white LED light-emitting materials. Using high-temperature solid phase prepared BaMoO 4 : Eu 3 phosphors, using X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrometer performance of the sample were tested. XRD results showed that at 800 ℃ available BaMoO 4 pure phase, BaMoO 4 tetragonal; Scanning electron microscopy showed that the sample particle shape comparison rules, dispersion than Good, particle size between 1 ~ 2μm. Excitation spectrum consists of a broadband and at 350nm after several line spectrum composed of broadband does not belong MoO 4 2 - energy absorption band, but vested in Eu 3 -O2-charge transfer absorption band (CT), line spectrum belongs to Eu 3 of f-f excitations absorption. Emission spectra from the 5D0-7F1 (591nm), 5D0-7F2 (615nm), 5D0-7F3 (654nm) and 5D0-7F4 (702nm) four peaks, whose red 5D0-7F2 transition emission strongest radiation, corresponding to Eu < sup> 3 of the electric dipole transitions. Studied Eu 3 doping concentration on BaMoO 4 : Eu 3 phosphor emission peak intensity at 615nm at the impact and found that Eu 3 doping concentration is 20mol%, the emission peak intensity has the maximum value, Eu 3 dopant concentration greater than 20mol%, the emission peak intensity decreases, concentration quenching occurs effect.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid nature of the > Optical Properties > Luminescence
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