Research On Rare Earth Doped Multi-Wavelength Sensitive Lead Fluoride Luminescent Materials

Rare-earth doped fluoride-based luminescent materials have received extensive attention due to their low phonon energy,large band gap and high luminous efficiency.In most cases,the research on fluoride luminescent materials mostly focuses on the up-conversion（UC）performance.However,research on the down-conversion（DC）have rarely been reported.In this dissertation,we prepared PbF₂:Er³⁺,Yb³⁺and PbF₂:Nd³⁺,Er³⁺,Yb³⁺bidirectional conversion phosphors by the high temperature solid state reaction method,which can convert both near-ultraviolet light and infrared light（808nm,980 nm,1064 nm,and 1550 nm）into visible light.The down-conversion and up-conversion multi-wavelength sensitive luminescence mechanisms of the Er³⁺/Yb³⁺,Nd³⁺/Er³⁺/Yb³⁺co-doped PbF₂ bidirectional conversion phosphors were discussed in detail by discussing the energy transfer process among different rare earth ions.In order to expand application of the phosphor,the PbF₂:Er³⁺,Yb³⁺up-conversion thin film were fabricated by magnetron sputtering technique and spin coating method.The main research contents and results are as follows:（1）We prepared the multi-wavelength sensitive PbF₂:Er³⁺,Yb³⁺phosphors by the high temperature solid state reaction method.We analyzed the phase structure and luminescent properties of the phosphors by X-ray diffraction and fluorescence spectroscopy,the optimal sintering temperature and the holding time were 650℃and 1.5 h.Under 980 nm,1064 nm and 1550 nm excitation,the luminescence intensity of samples reach the maximum when Yb³⁺doping concentration were 18 mol%,18 mol%and 14 mol%,respectively.Under378nm excitation,the luminescence intensity of green emssion gradually decreases and the red emssion gradually increases with increasing Yb³⁺concentration.（2）We prepared PbF₂:Nd³⁺,Er³⁺,Yb³⁺phosphors by adding Nd³⁺ions.Nd³⁺ion as a co-sensitizer and absorber can effectively enhance the up-conversion luminescence of the samples at 808 nm excitation.The phosphors with different Nd³⁺concentration were synthesized,the phase structure,luminescence properties and lifetime of the samples were inveatigated in detail.Under 808 nm excitation,the up-conversion luminescence property and the lifetime of PbF₂:Nd³⁺,Er³⁺,Yb³⁺samples reach the maximum when Nd³⁺doping concentration is 3 mol%.However,at 378 nm and 980 nm excitation,the luminescence intensity gradually decreases with increasing Nd³⁺concentration due to the reverse energy behavior between Er³⁺→Nd³⁺ions.（3）The up-conversion thin film was fabricated by magnetron sputtering and spin coating method on quartz glass and slide substrate separately.The phase structure,up-conversion luminescence property,transmittance and microscopic appearance of thin film were analyzed.For the experimental results of spin coating method,the optimal combinations of the number of spin coating layers,the rubber powder ratio and substrate were 3,1:2 and quartz glass.For magnetron sputtering method,the optimal preparation conditions of the sputtering time,annealing temperature and time were 1.5 h,500°C and 30min.