Investigation Of Preparation And Luminescence Properties Of Rare Earth-Doped Aluminate

Rare-earth ion activated aluminate materials are extensively studied,owing to their high luminous efficiency,stable chemical properties and lower relative cost.At present,the solid state method is still a preferred route for the preparation of aluminate luminescent materials. The disadvantages are its hard uniformity in raw material and particle agglomeration of products.Moreover,commercial aluminate phosphors also show deficiency in intensity decay and chromaticity shifting by temperature increasing.In this paper,the improved preparation method was studied to increase the intensity of aluminate phosphor and the decay mechanism by raised temperature was discussed extensively.The major results are listed below:1.To combine with different kinds of fluxes,the YAG:Ce³⁺ yellow phosphor was synthesized by solid-state reaction.The citric acid sodium was used firstly,combined with (NH₄)₂HPO₄ and H₃BO₃ simultaneously.The phosphor was characterized by means of X-ray Diffraction(XRD) and Scanning Electron Microscope(SEM).The results show that by the additive of citric acid sodium,the growth of phosphor particles could be loose,well dispersing and non aggregation.When the content of Ce is 0.06,the mole ratio of Y:Al is 2.94:5 and the mass ratio of B:P:Na is 2.0:1.5:2.0,the luminescence property of YAG:Ce³⁺ phosphors are effectively controlled and show high crystallinity.2.The temperature-dependent excitation and emission spectra of the YAG:Ce³⁺ phosphor were investigated.It is found that the luminescence intensity by 340 or 460 nm wavelength excitation decrease by different trend with increasing temperature.The activation energies areâ–³E₁=0.136 andâ–³E₂=0.125 eV for 340 and 460 nm bands were fitted according to an Arrhenius function.The qualitative analysis of this phenomenon is also made through configuration coordinate model.In addition,the fluorescence spectrum,fluorescence lifetime and thermoluminescence spectrum by different content of Al were studied.It is concluded that the change of Aluminate quality will affect electron trapping numbers and lower luminescence intensity and fluorescence lifetime of Ce³⁺.3.A new synthesis method-composite preparation was used to obtain Tb³⁺ doped SrAl₂O₄ phosphor materials.The crystallinity,morphology and spectrum properties of the samples were investigated by XRD,SEM and Fluorescent Spectrophotometer,respectively. Comparing with traditional solid-state reaction,the crystallinity and emission intensity of the SrAl₂O₄:Tb³⁺ phosphor were improved.