| In this paper, from the preparation method to photoluminescence properties and luminescence mechanism, the research progress of pure and doped Sr2CeO4 phosphors were reviewed. To our best knowledge, for the first time, pure and doped Sr2CeO4 nano-sized phosphors, was successfully synthesized through citrate-gel method, after optimizing preparation conditions. This paper also investigated the structures, spectral characters, luminescence behaviors, particles size and morphology of pure and doped Sr2CeO4 phosphors by X-ray diffraction (XRD), FT infrared, Raman spectrum, thermogravimetric analysis (TG), ultraviolet and visible absorption spectrum, photoluminescence spectrum, transmissions electron microscopy (TEM) and atomic force microscopy (ATM), respectively. The conclusions are as follows:As for preparation of Sr2CeO4 phosphor, based on the crystal structure and luminescent property, the citrate-gel method is better than solid-state method at high temperature, because this phosphor can be synthesized at lower sintering temperature through citrate-gel route. This as-prepared Sr2CeO4 phosphor with white body-color, contains little impurities phase and the Sr2CeO4 phase is dominant. The Sr2CeO4 phosphor particles are sphere and have particles size 40-50nm and narrow size distribution. There is no need for it to be milled before application in lamps or other luminescence display field. Under excitation with irradiation of UV rays, these nano-phosphors exhibit strong blue-white luminescence, which peaks at about 470 nm. Therefore, it has good potential for application as a blue-white phosphor.Luminescence properties of Sr2CeO4 nano-phosphors can be affected by preparation conditions, in which the sintering temperature is dominant. When the sintering temperature, the ratio of citric acid to metal ions and the pH value of precursor solution is 1000癈, 3 : 1 and 7, respectively, it owns maximum emission intensity of photoluminescence.In the present paper, the luminescence properties, concentration quenching, energy transfer and effect of co-doping ions on the luminescence of Sr2CeO4:Eu3+ phosphor are also studied in details. The as-prepared Sr2CeO4:Eu3+ nano-sizedsamples, with white body-color and smaller mean particle size, exhibit a strong red emission under UV excitation. The excitation spectra shows a broad intense band and a number of small peaks centered at wavelengths extending from 380 nm to 540 nm corresponding to the inner 4f-shell excitations of Eu3+ (the strongest one is at 466 nm for 7F0-5L6). From the measured fluorescence spectra of Sr2CeO4:Eu3+ nano-phosphors, apart from transitions emission of 5Do excited state 5Do -?F|(585 nm),5D0 @7F2(616 nm),5D0 @7F3(655 nm),5D0@7F4 (704 nm), the following transitions emission from 5D1 excited state of Eu3+ 5D1@7F0 (509 nm),5D1@7F1 (534 nm),5D1@7F2 (554 nm) have been observed. It is revealed that the quenching concentration for the 5Do-7F2 emission of Eu3+ in this host is as high as 22 mol%. This may be due to the facts that the probability of cross relaxation is lower and energy loss is very little in the course of energy transfer between two chains or inter-chain. In addition, energy transfer from host Sr2CeO4 to activator Eu3+ was observed inSr2CeO4: Eu3+ phosphor. The host-to-activator energy migration mechanism may be carried out by exchanging between two chains or inter-chain in Sr2CeO4 host lattice. The relative fluorescence intensities of rare earth ion (La3+-,Gd3+-, and Y3+- ) or alkaline ion( Li+-, Na+-, K+-) co-doped Sr2CeO4: Eu3+ phosphors were higher than that of Eu3+-doped Sr2CeO4.This emission enhancement mainly resulted from the fact that formation of energy transfer network after rare earth ion (La3+-,Gd3+-, and Y3+- ) or alkaline ion ( Li+-, Na+-, K+-) co-doping into Sr2CeO4 : Eu3+ phosphor.All the results revealed that the as-prepared Sr2CeO4 nano-sized phosphor has better theoretical and application potential. It is an excellent host and luminescent material, which owns splendid development prospects. It is predicted that a... |
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