Research On Preparation And Application Of Fluoride-based Ultrafine Phosphor

Rare earth-doped fluoride upconversion luminescent materials have been widely studied because of their advantages of good color purity,high luminous efficiency,and diverse preparation methods.At present,it is widely used in many fields such as infrared anti-counterfeiting,up-conversion three-dimensional display,biological detection and treatment,and fluorescent composite materials.Studies have found that in fluorescent composite materials,the smaller the particle size of the phosphor can reduce the cost of the composite material,and can increase the density of the fluorescent composite material.Therefore,fine-particle up-conversion luminescent materials have become the focus of attention in the field of frontier science and technology.Therefore,this paper has systematically studied the lead fluoride-based upconversion luminescent materials doped with rare earth ions and used phosphors to prepare fluorescent composite materials.The prepared up-conversion luminescent materials and fluorescent composite materials were characterized by XRD,SEM,emission spectroscopy,variable temperature spectroscopy,infrared spectroscopy and other test methods,and the morphology,size,structure,and luminescence properties of the samples were further analyzed.The main research content and results include the following aspects:1.Using PbF2 as the matrix material,the high-temperature solid-phase method was selected and cations were introduced to prepare the ternary fluoride matrix phosphor.The results show that the addition of a certain molar percentage of Mg²⁺and Ca²⁺ions improve the up-conversion luminescence performance of the sample.The prepared phosphor was subjected to ball milling and pulverization,and the average particle size after ball milling was D₅₀=2.2686μm.Therefore,it can be concluded that the high-temperature solid-phase method cannot obtain small particle size nano-powders.2.Using PbF2 as the host material and adopting the co-precipitation method,three up-conversion luminescent materials were prepared,the sensitizer was Yb³⁺ions,and the activator ions were Er³⁺,Ho³⁺,and Tm³⁺ions.The structure and luminescence performance of the three up-conversion luminescent materials are analyzed.The results show that the three up-conversion luminescent materials have the maximum luminous intensity under excitation at 980 nm when the respective holding time is 1.5 h,and the average crystal grain size of the obtained phosphors is all below 100 nm.When the molar ratio of Er³⁺/Yb³⁺ion doping is 1:9 and the sintering temperature is 390℃,Er³⁺ion as the luminescent center ion produces green light emission peaks at 520 nm and 540 nm,corresponding to²H_11/2→⁴I1_5/2,⁴S_3/2→⁴I1_5/2 energy level transition;Ho³⁺/Yb³⁺ion doping molar ratio is 1.5:9,sintering temperature is 370℃,Ho³⁺ion as the luminescent center ion produces green and red upconversion emission at 542 nm and 645 nm,originating from ⁵F₄⁴S₂→⁵I₈ and ⁵F₅→⁵I₈energy level transition;Tm³⁺/Yb³⁺ion doping molar ratio is 0.3:9,sintering temperature is390℃,the emission peaks of Tm³⁺ions are at 479、656 and 689 nm,respectively,for the¹G₄ of Tm³⁺ions→³H₆,¹G₄→³F₄and ³F₃→³H₆ energy level transitions.3.The phosphor-PMMA fluorescent composite material is prepared by the bulk polymerization method.A comprehensive analysis of the structure,up-conversion luminescence performance,transmission performance and microscopic morphology of single-doped fluorescent composites and double-doped fluorescent composites draws conclusions.The results show that the phosphor is wrapped by PMMA and the phosphor is successfully doped into PMMA.In the single-doped fluorescent composite material,when the PbF2:Er³⁺,Yb³⁺phosphor doping amount is 0.2 wt%,the transmittance is 53.2%,and when the doping amount is 2.0 wt%,the transmittance is 6.7%.In the double-doped fluorescent composite material,when the doping content of PbF2:Tm³⁺,Yb³⁺phosphor is0.2 wt%,the transmittance is 42.3%,and when the doping content is 1.0 wt%,the transmittance is 3.1%.