Synthesis Methods Of Doped Nano Luminescent Materials And Luminescence Properties Before And After Laser Induction

Rare earth elements refer to 17 elements comprising 15 elements of the lanthanide series and yttrium（Y）and scandium（Sc）of the third sub-group as contained in the Periodic Table of Elements.With the presence of distinctive 4f energy level structure,these elements turn out to be of extraordinary optical properties subject to the excitation of UV light.Moreover,rare earth element ions can often be used as an effective luminescent center or activation center,thus making it widely used in inorganic luminescent materials and organic luminescent materials.Rare earth phosphors as prepared from rare earth elements can be suitably used for various applications,including cathode ray tubes,trichromatic energy-saving lamps,panel displays,and high-definition displays,suggesting its broad market prospects.However,because most of the previous rare earth phosphor components contain sulfur oxides with lower thermal stability and stronger environmental impact after decomposition,the application of conventional rare earth phosphors has been subject to limitations.In contrast,non-sulfur oxide rare earth phosphors tend to have better thermal stability,produce no harmful gas when used,and possess better luminescence properties.Given this,non-sulfur oxide rare earth phosphors have been extensively studied,and it is of great significance to enhance the properties of non-sulfur oxide rare earth phosphors.In this paper,Y₂O₃:Eu³⁺and Gd₂O₃:Eu³⁺as nano-fluorescent powders prepared using different synthesis methods and different combustion agents were discussed.The synthesis mechanism of the two nano-fluorescent materials was compared,the factors influencing the surface morphology of products and the effects of different annealing temperatures were examined,and the differences in luminescence properties before and after laser induction were identified.This work is expected to provide technical support and theoretical ground for subsequent researchers.The research questions analyzed here and the results obtained from discussion are described below:1.Y₂O₃:Eu³⁺as nano-fluorescent material powder was prepared using low temperature combustion（LTC）and sol-gel method（SG）,respectively.The effects of different preparation method and annealing temperatures on the optical properties of Y₂O₃:Eu³⁺were examined.XRD and TEM test results show that the Y₂O₃:Eu³⁺power obtained is a tetragonal construction.The rise of annealing temperature was accompanied with the increase in the size of Y₂O₃:Eu³⁺particles.The charge transfer band（CTB）was found blue-shifted,indicating a higher spectral intensity.As is obtained from PL spectral analysis,strong peaks appeared at 594 nm and 612 nm,which can be attributed to ⁵D₀→⁷F₁ transition of the magnetic dipole charge and⁵D₀→⁷F₂ transition of electric dipole charge,the annealing temperature imposed a significant influence on the charge transition rate between them.FTIR spectral analysis shows that the low emission intensity led to weakened spectral intensity and degraded optical properties of the materials.It was further found that the spectral intensity varied greatly with the increase of laser induction time,along with significantly different spectral density before and after laser induction.2.The characteristics of lattice structure,morphology and photoluminescence of the nano-fluorescent materials,Nano-Y₂O₃ and Nano-Gd₂O₃,doped with Eu³⁺before and after laser induction were studied.FE-SEM and TEM test results show that the morphological change of material varied with the annealing temperature.Their emission spectrum and excitation spectrum indicate that laser induction had a significant effect on the spectral peak.The position of the emission peak was not related to laser radiation time,but its intensity varied greatly with the laser radiation.The effects of the charge transfer band were attributable to the increase of surface defects and energy transfer channels as a result of laser radiation.In addition,the intensity difference of ⁵D₀–⁷F₂ transition occurring in the electric dipole charge was subject to the annealing temperature.3.In order to identify the effects of different combustion agents on the behaviors of the nano-fluorescent material Nano-Y₂O₃ doped with Eu³⁺,the urea,oxalic acid,citric acid and glycine（labeled as YOE-U,YOE-O,YOE-C and YOE-G respectively）were selected as combustion agents respectively,the Y₂O₃:Eu³⁺sample was synthesized using low temperature combustion（LTC）.In addition,the variation of their properties on the excitation spectrum and the emission spectrum was examined under different annealing temperatures and laser radiation,the spectrum peak of Y₂O₃:Eu³⁺was found largely blue-shifted.According to the test results,higher annealing temperature was not always the best option,this should be determined by different combustion agents.Laser radiation would increase the PL intensity of these samples at the annealing temperature of 800°C,while partially increase the PL intensity of these samples at the annealing temperature of 600°C.The YOE-U sample had the higher luminous intensity than any of the samples synthesized with any other combustion agent.Of all the samples,the PL intensity of the YOE-U sample reached the highest after laser irradiation at 800°C.According to the SEM results,the smooth surface of the prepared material would reduce the surface effect,which will be more favorable for charge transfer.The decrease of surface defects was accompanied with the increase of photoluminescence（PL）intensity.The PL behaviors were not dependent on the presence of pore inside,but related to the material thickness,surface smoothness,and surface pore size.4.Urea,oxalic acid,citric acid and glycine（labeled as GOE-U,GOE-O,GOE-C and GOE-G respectively）were selected as combustion agents respectively,the Gd₂O₃:Eu³⁺sample was synthesized using low temperature combustion（LTC）.Through multiple tests and characterizations,Nano-Gd₂O₃ prepared using this method was also found blue-shifted,but with the parameter change induced by temperature and laser,such behaviors tended to be different.For the excitation spectrum,the laser radiation at the sintering temperature of 600℃had no substantial influence on the excitation spectrum.After the sintering temperature of 800℃and laser induction,the peak intensity of the excitation spectrum of the samples obtained by using urea as combustion agent slightly increased,while that of the samples prepared using other materials decreased significantly.For the emission spectrum,the effects of laser radiation on their behaviors slightly weakened.