Synthesis,Temperature Sensing Property And Photothermal Conversion Property Of Rare Earth Doped NaLnF₄ Fluorescent Particles

With the rapid economic development,people have put forward higher requirements on the environmental protection and energy saving of the materials and the efficient cleaning of the energy used for vehicles tools.Rare earth luminescence,catalysis,permanent magnets and hydrogen storage materials have been used in a large number of applications in all aspects of the vehicle.Among them,rare earth materials with good temperature sensing and photothermal conversion properties have potential application in the field of maintenance of precision electronic instruments for vehicles and microbial inactivation of ship ballast water.In this dissertation,we synthesize the rare earth ion-doped NaLnF₄ particles by different methods,and study their upconversion luminescence properties,temperature sensing and photothermal conversion properties,temperature quenching phenomenon.The main research results are as follows:?1?The rare earth doped NaYF₄ particles are synthesized by the traditional and microwave hydrothermal method and co-precipitation method.The effects of pH,reaction temperature and chelating agent on the product are investigated.?2?NaLuF₄ particles are prepared by the traditional hydrothermal method.The feasibility of NaLuF₄:Yb³⁺/Tm³⁺ used for temperature detection was verified by Yb³⁺/Er³⁺ codoped NaLuF₄ particles,and the photothermal conversion property of NaLuF₄:Yb³⁺/Tm³⁺ is studied.The results show that Tm³⁺ is promising for temperature detection as same as Er2+.?3?The ?-and ?-NaYF₄:Yb³⁺/Er³⁺ particles are synthesized by microwave hydrothermal method.Compared the upconversion luminescence properties,temperature sensing and photothermal conversion properties of the two samples,we find that the ?-NaYF₄:Yb³⁺/Er³⁺ shows greater upconversion luminescence and better temperature sensing properties.?4?NaYF₄:Yb³⁺/Er³⁺ particles are obtained by hydrothermal method,the sample shows good temperature sensing and photothermal conversion properties under 1550 nm laser irradiation.The temperature quenching of green luminescence is studied through the established physical model,the result shows that the non-radiative relaxation is the main reason for the quenching phenomenon.?5?NaYF₄:Sm³⁺/Yb³⁺@NaYF₄:Er³⁺/Yb³⁺and NaYF₄:Dy³⁺/Yb³⁺@NaYF₄:Er³⁺/Yb³⁺core-shell structure nanoparticles are respectively synthesized by pyrolytic decomposition method,the NaYF₄:Er³⁺/Yb³⁺ shell structure of two samples have good temperature sensing property,and the core structure have obvious photothermal conversion effect under 980 nm excitation,but the NaYF₄:Sm³⁺/Yb³⁺ core structure shows more significant photothermal conversion effect.?6?NaYF₄:x mol%Er³⁺/Yb³⁺ particles are prepared by combustion combined with high temperature solid state method,the Judd-Ofelt parameters are calculated by diffuse reflectance spectroscopy.