Study On Preparation And Surface Modification Of Y₂O₃:Eu³⁺ Luminescent Materials

At present,a very important class of rare earth luminescent materials belongs to three primary color luminescent materials,which are rare earth luminescent materials obtained by activation of three different rare earth ions,blue,green and red.Y₂O₃:Eu³⁺can be used as a red phosphor material,which is composed of substrate material Y₂O₃ and excited ion Eu³⁺.As we all know,Yttrium oxide（Y₂O₃）is a very important rare earth oxide belonging to the cubic system,it has excellent chemical stability and physical and mechanical properties,can be used as a relatively ideal rare earth luminescent matrix material.Europium（Eu）is a typical lanthanide element,which has the highest reactive activity among all lanthanide elements,and its outermost electron is easy to transition after excited to produce fluorescence emission and fluorescence excitation.Europium ion(Eu³⁺)doped into Y₂O₃ substrate,the Y₂O₃:Eu³⁺luminescent material can be used as the red powder in rare earth trichromic phosphors.It has the advantages of high quantum efficiency,good color purity,good photodecay characteristics,suitable emission wavelength,etc.,and has been widely used in fluorescent lamp,color display,chemical fiber ink media and other technical fields.At present,in the preparation of materials,it is not easy to prepare Y₂O₃:Eu³⁺luminous materials with good morphology simply and quickly in a short time,and the luminous performance of the prepared materials is not high;In addition,there are a large number of hydroxyl groups on the surface of Y₂O₃:Eu³⁺,strong hydrophilicity,poor lipophilicity,so it can not be used in some oily organic media.In order to solve these problems,the improved coprecipitation method was adopted in this paper to achieve the goal of preparing spherical Y₂O₃:Eu³⁺luminescent materials in a relatively short time and efficiently.The morphology,structure,elemental composition and luminescence properties of samples at different calcination temperatures（900℃,1000℃,1100℃）were investigated.The surface of Y₂O₃:Eu³⁺luminescent materials was modified by hexadecyltrimethoxysilane（HDTMS）.Y₂O₃:Eu³⁺luminous materials were prepared by an improved coprecipitation method.The method adds ultrasonic mixed precipitation and oil bath heating to the steps of the traditional co-precipitation method,and can be prepared with ultrafine particles and uniform particle size distribution powder,small particles without ball milling,and the product phase purity is high,the preparation equipment is simple and easy to operate.Then,the effects of different calcination temperatures（900℃,1000℃,1100℃）on the morphology,crystal structure and luminescent properties of the prepared samples were studied,and the mechanism of the luminescent properties of the materials doped with europium ion was analyzed.The sample prepared at the calcination temperature of 1000℃has a better spherical shape,and a large number of regular spherical particles appear,and the particles are relatively uniform and the particle size is relatively small.The test shows that Y₂O₃:Eu³⁺samples prepared at 1000℃have better crystal structure,and the diffraction peak intensity of each crystal surface is the largest.The valence state of Y element is+3,and the valence state of Eu element is also+3,indicating that the sample prepared by co-precipitation method has the element component valence very in line with the material standard,and also has a high emission intensity.On this basis,the prepared Y₂O₃:Eu³⁺luminous materials were modified with different proportions of hexadecyltrimethoxy（HDTMS）surface hydrophobicity,morphology,element composition and fluorescence properties before and after modification were investigated.The results show that when the mass ratio of Y₂O₃:Eu³⁺to HDTMS is 1:1.6,the modification effect is the best,and the contact angle for water is about 143°.The changes of functional groups before and after modification of Y₂O₃:Eu³⁺were obtained by FTIR analysis.It was confirmed that the surface of Y₂O₃:Eu³⁺was successfully grafted with-CH₃,-CH₂-and C-O organic functional groups.The results of TG analysis showed that the bonding quality of Y₂O₃:Eu³⁺surface-CH₂（CH₂）₁₄CH₃ organic hydrophobic long chain increased with the increase of the addition of HDTMS.SEM-EDS results showed that the modification process had little effect on the particle size of Y₂O₃:Eu³⁺,and the increase of Si and C in HDTMS-Y₂O₃:Eu³⁺also confirmed that the hydrophobic long chain of HDTMS was successfully grafted to the surface of Y₂O₃:Eu³⁺.XRD results show that the crystal structure of Y₂O₃:Eu³⁺is not damaged after modification.PL spectral analysis shows that the excitation spectrum,emission spectrum and emission intensity of the modified Y₂O₃:Eu³⁺luminous materials are basically not affected.In addition,the quantum yield（QY）of the modified HDTMS-Y₂O₃:Eu³⁺material is 77.85%,and the modified Y₂O₃:Eu³⁺material still has a good luminescence effect.In conclusion,our preparation method of Y₂O₃:Eu³⁺is simple,rapid,low cost,and has good hydrophobic modification effect.This study can provide reference for the preparation of hydrophobic and oleophilic Y₂O₃:Eu³⁺luminescent materials and their application in organic media.