Preparation And Luminescent Properties Of Rare Earth Doped Vanadate Phosphors LnVo₄:R³⁺

Rare earth vanadate phosphors have broad application prospects in energy-saving lamps,semiconductor lighting and displays owing to their excellent luminous properties.However,since the price of rare earth is relatively high and it is a non-renewable resource,the demand for effective use of rare earth resources（such as the preparation of phosphors with small particle size and uniform distribution）is increasing.The sol-gel auto-combustion method has the advantages of high production,small size,simple experimental equipment,short experimental time and low energy consumption value.Therefore,it is important to study the vanadate luminescent materials by sol-gel auto-combustion method.The YVO₄powder with a porous structure was prepared by the self-propagating sol-gel combustion method.After annealing at 500℃,polycrystalline polyhedral YVO₄ particles with good crystallinity were obtained with a particle size of 0.2-2μm.The distribution was relatively uniform.The space group is I4₁/amd belongs to tetragonal system.In this experiment,it is first time to prepared a series of rare earth substituted vanadate phosphors using the sol-gel auto-combustion method:YVO₄:R³⁺（R=Eu,Sm,Yb/Er,Yb/Tm）;LaVO₄:R³⁺（R=Ho,Sm,Er）;GdVO₄:R³⁺（R=Ho,Sm,Er,Yb/Er）.The samples were examined by XRD,SEM,fluorescence spectrum or other testing methods.The effects of different process conditions,annealing temperatures,and activator ions on the phase structure,morphology,and fluorescence properties of the phosphor were studied in detail.The emission spectra of LaVO₄:R³⁺（R=Ho,Sm,Er）;YVO₄:R³⁺（R=Eu,Sm,Yb/Er,Yb/Tm）were analyzed,and it was found that the peak position of the occurrence was completely consistent with the activator rare earth ion The position of the characteristic emission peak,and no characteristic peak of VO₄^3-was found,indicating that between VO₄^3-and the activator rare earth ion The energy transfer was efficient.In addition,the energy transfer mechanism of YVO₄:R³⁺（R=Eu,Sm,Yb/Er,Yb/Tm）samples was analyzed.The results of XRD and SEM were performed on the GdVO₄ sample to find the best experimental conditions:when the annealing temperature was 800℃,pure phase GdVO₄ sample was obtained,and the particle size of the sample increased as the temperature increased.In addition,by analyzing the emission spectrum of the sample,the emission spectrum of different rare earth ions under the irradiation of the excitation light source of the sample was obtained.The relationship between energy transfer inside the sample when doping with different R³⁺（R=Ho,Sm,Er,Yb/Er）ions was also discussed.