| Rare-earth ion-doped nanometer-luminescent materials have the characteristics of stable emission spectrum,narrow spectral band,long lifetime,wide luminescent coverage,and stable chemical properties.They gradually become an important mainstream material in luminescent materials and are widely used in various biomedical fields.The rare earth doped nanometer materials with near-infrared excitation and near-infrared emission can be used as a fluorescent probe,this application has great advantages in biological imaging.In this paper,the substrate we use is tetra-fluoride,Eu3+ ions doped with NaYF4 are prepared by co-precipitation method,and use transmission electron microscopy to analyze and change the structure of the material.NaGdF4:Nd3+ nanoparticles were prepared by co-precipitation method and solvent thermal method respectively,and their luminescence properties were studied.Based on the luminescence performance of NaGdF4:Nd3+ nanometer material,temperature sensing was conducted by using the fluorescence intensity of Nd3+ emission peak,and the main factors affecting its luminescence performance and temperature sensitivity were investigated.This thesis mainly completes the following work:(1)NaYF4:5%Eu3+ nanometer samples was made by co-precipitation method,and using a transmission electron microscope(TEM)on the phase,structure analysis,prove that the measured nanometer materials is uniform particles and has good dispersion,it is the hexagonal phase NaYF4:5%Eu3+ which average particle size is around 77 nm.The electron beam irradiation experiment was carried out on the sample.It was found that the NaYF4:5%Eu3+ samples of the six square phase changed from the edge to the center gradually from the hexagonal phase to the cubic phase after a certain time of irradiation.At the same time,we also study the luminescent properties of Eu3+,hoping to further verify the structural changes of nanometer materials.(2)Hexagonal phase NaGdF4:Nd3+ nanometer samples were synthesized using co-precipitation and solvent heat.The nanoparticles prepared by cop-precipitation method have good dispersion,uniform particle size,average size of particle size at about 8nm,and NaGdF4:Nd3+ nanoparticle prepared by solvent thermal method has irregular morphology with slight agglomeration.Testing the spectra of samples,using 808 nm wavelength laser to motivate nanoparticles,in near infrared region observed the characteristics of light emitting of Nd3+,4F3/2→4I9/2 energy level transition of Nd3+ will have energy level splitting phenomenon under the different temperatures,and this phenomenon relying on the change of temperature,so we analyzed the principle of temperature measurement using fluorescence intensity ratio which produced by Nd3+energy level splitting.(3)Studied the influence of Nd3+ different doping concentrations on luminous performance and temperature sensitivity of NaGdF4:Nd3+ nanoparticle prepared by solvent thermal method,We found that when the doping concentration increased from 0.2%to 3%,the fluorescence intensity increased with the concentration,and when the doping concentration was greater than 3%,the fluorescence quenching occurred,and the higher the concentration with the greater the quenching degree.Therefore,when the doping concentration of Nd3+ was 3%,the concentration was the optimal doping concentration,and the NaGdF4:Nd3+ nanoparticles has the strongest luminescence.We tested temperature fluorescence spectrum with different Nd3+ doped concentration from 15 ℃ to 65 ℃,the results show that nanoparticles with the change of temperature sensitivity is no direct relationship with the fluorescence intensity,the best relative sensitivity is 0.10%K-1 of NaGdF4:1%Nd3+ nanoparticles.(4)We explored the temperature sensitive properties of water soluble NaGdF4:Nd3+,Yb3+ nanoparticles prepared by solvent heat method and analyzed the temperature measurement mechanism with energy transfer between Nd3+ and Yb3+.Investigating the effects of Nd3+,Yb3+ doped concentration for temperature sensitivity.Testing the fluorescence spectrum of NaGdF4:1%Nd3+,5%Yb3+、NaGdF4:3%Nd3+,15%Yb3+ and NaGdF4:5%Nd3+,25%Yb3+ from 15 ℃ to 65 ℃,and get the rule of the ratio of the fluorescence intensity of the samples with different doping concentrations varies with the temperature.Among them,NaGdF4:1%Nd3+,5%Yb3+ nanoparticles was the best,and its relative temperature sensitivity was up to 0.37%K-1,the temperature sensitivity of the single doped Nd3+ sample is obviously improved. |
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