Construction And Performances Of Rare Earth Fluorides Flexible One-Dimensional Nested Structures

Nano-materials with coated structure have excellent characteristics such as low density,high surface area and empty space,which makes them have important research value in many fields such as biomarkers,medical imaging,up/down conversion luminescence and catalysis.Gadolinium-based rare earth fluorides are widely used in of nano-luminescent materials because of their unique and excellent luminescent properties.It is urgent to need the unique coated core-shell materials with the development of society and the demand of science and technology.At present,many synthetic methods have been used to prepare encapsulated structural nanomaterials with voids.However,there are few reports on the preparation of one-dimensional linear and tubular structural fluorides nanofibers doped with rare earth ions by electrospinning technology.Electrospinning has become an effective technology to prepare one-dimensional nano-materials because of its simple process,controllable fiber size and ultra-high specific surface area.Therefore,it is an important research topic to synthesize one-dimensional nanofibers with coated structure by electrospinning technolog.In this dissertation,GdF₃codoped with rare earth ions one-dimensional wire-in-tube structured nanofibers are designed and constructed by combining electrospinning technology with fluorination calcination technology.The structure,morphology and luminescence properties of samples have been systematically studied.The specific research contents include:1.A novel,simple and efficient method was designed,and one-dimensional nanofibers with GdF₃:Yb³⁺,Ho³⁺@void@SiO₂wire-in-tube structure were successfully constructed by effectively combining electrospinning technology with fluorination roasting technology.The morphology and structure of the samples were studied in detail,and energy transfer mechanism and luminescent properties were deeply discussed.Finally,the formation mechanism of one-dimensional nanofibers with wire-in-tube structure was put forward.At the excitation of 980 nm and 448 nm,respectively,one-dimensional nanofibers with GdF₃:Yb³⁺,Ho³⁺@void@SiO₂wire-in-tube structure realized dual-mode luminescence with up-conversion and down-conversion.2.One-dimensional nanofibers with GdF₃:Eu³⁺,Er³⁺@void@SiO₂and GdF₃:Yb³⁺,Er³⁺,Eu³⁺@void@SiO₂wire-in-tube structure were successfully constructed by a new technology combining uniaxial electrospinning technology with fluorination roasting technology.The morphology and structure of the samples were studied in detail,and energy transfer mechanism,luminescent properties and formation mechanism were deeply discussed.By adjusting the concentration of doped ions and using different excitation wavelengths of 374 nm,394 nm and 980 nm,the emission spectra are obtained,and up-and down-conversion luminescence and light color adjustable luminescence of the sample are realized.3.GdF₃:Yb³⁺,Tm³⁺@void@SiO₂wire-in-tube structured one-dimensional nanofibers were synthesized by combining electrospinning technology with single crucible fluorination technology.The morphology and structure of the samples were studied in detail,and energy transfer mechanism,luminescent properties and formation mechanism were deeply discussed.Wire-in-tube structured nanofibers with large internal and external gaps have potential application value in nano-sensing,biological tracing and other fields.In this thesis,silica-coated rare earth fluorides up-conversion and down-conversion dual-mode luminescent one-dimensional wire-in-tube structured nanofibers were successfully constructed based on the electrospinning technology,and some meaningful research results were obtained,which provided a new idea for the preparation of coated structured nanomaterials with tunable light color and excellent multifunctional characteristics.