Prparation And Properties Of Rare Earth Vanadate Luminescent Materials

Rare earth luminescent materials are one of the most important rare earth functional materials,and play an increasingly important role in scientific and technological progress and social development.Rare earth vanadate-based luminescent materials with high energy conversion efficiency,high thermal conductivity,high thermal stability and high vacuum UV absorption cross-section,have been widely used in lighting and display equipment.However,emerging applications in solid-state lasers,naked eye 3D displays,and fluorescent biomarkers have raised higher performance requirements for vanadate-based rare earth luminescent materials.Therefore,it is important to study the enhancement of the fluorescence intensity of rare earth vanadate luminescent materials by different methods.In this paper,europium doped vanadate(GdVO4:Eu3+ and YVO4:Eu3+)nano luminescent materials were studied,and their luminescence properties were modified by three different methods,X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),ultraviolet-visible absorption spectroscopy(UV-Vis),photoluminescence spectra(PL)were used to analyze the microstructure and fluorescence properties of the prepared samples.The main contents of this paper are as follows:(1)Firstly,GdVO4:Eu3+luminescent materials were modified by alkali metal ion co-doping method.GdVO4:Eu3+,R+(Li+,Na+,K+)luminescent materials were successfully prepared by hydrothermal method.The effects of different R+co-doping concentrations on the crystal structure,microstructure and emission intensity of GdVO4:Eu3+,R+luminescent materials were investigated.The results showed that with the increasing of R+co-doping concentration,the R+ co-doping pattern was changed from substitutional occupation to interstitial occupation,which lead to the continuous distortion of lattice structure,and the optimum emission intensity was obtained when co-doping with 10mol%Li+,8mol%Na+and 6mol%K+.The effect of co-doping of 10mol%Li+,8mol%Na+ and 6mol%K+on the quenching threshold of Eu3+ was also studied.It was found that the co-doping Li+could effectively alleviate the quenching effect and improved the photoluminescence performance.(2)Secondly,based on the co-doping of alkali metal ions,the effect of heat treatment on the fluorescence properties of GdVO4:Eu3+luminescent materials were investigated.The GdVO4:Eu3+,R+(Li+,Na+,K+)luminescent materials were heat treatment at 900? for 2 h under N2 atmosphere,The results showed that the crystallinity of the samples was improved and the emission intensity was significantly increased after heat treatment.The effects of matrix crystallinity and co-doping lattice defects on the fluorescence intensity,and the effect on the quenching threshold of Eu3+concentration were also studied.It was found that the lattice defects of the samples after heat treatment were reduced,and the quenching threshold of Eu3+was increased from 5mol%to 9mol%when 8mol%Na+and 6mol%K+co-doping.(3)Finally,YVO4:Eu3+luminescent materials were hybrid with gold nanoparticles,and the fluorescence properties of YVO4:Eu3+luminescent materials were enhanced by the surface plasmon resonance effect of gold nanoparticles.The effect of gold nanoparticles on the fluorescence properties of hybrid luminescent materials were studied,The results showed that the gold nanoparticles can not change the red characteristic emission spectrum of Eu3+for YVO4:Eu3+luminescent materials,and the emission intensity of hybrid nanoparticles were increasing with the growing of gold nanoparticles,which is due to the increasing of gold particles' size and the enhancement of local incidence field,leading to the increasing of fluorescence intensity.