Synthesis,Structure Control,and Properties Of Rare Earth Ions Doped Three Kinds Of Oxoacid Salts Based Luminescent Materials

Inorganic solid luminescent materials are widely applied in many fields such as lighting,information displays,and biomedicine due to their unique properties,and are closely related to people's lives.Among them,the rare earth luminescent materials exhibit many advantages such as clear emission lines,rich emission channels,high color purity,convenient synthesis,and good chemical stability due to their unique electronic layer structure.They are widely used in various fields of our daily life.Therefore,it is highly desirable for the synthesis and applications of new types of highly efficient rare earth luminescent materials with good physical and chemical stability.In this work,a series of novel rare earth-doped titanate(La₄Ti₃O₁₂),fluoroaluminate(Sr₃AlO₄F),and tungstate(La₁₀W₂₂O₈₁)luminescent materials have been prepared by the sol-gel method and electrospinning method,and the phase structure,morphologies,element composition,luminescence properties,and luminescence mechanism have been studied in detail.The main content is as follows:A series of new perovskite-type down-conversion La₄Ti₃O₁₂:Ln³⁺(Ln=Dy,Eu,Sm,and Tb)and up-conversion La₄Ti₃O₁₂:Yb³⁺/Ln³⁺(Ln=Er,Ho,and Tm)were prepared by the Pechini sol-gel method with citric acid as the complexing agent and ethanol as the solvent.The effect of doping concentrations and calcination conditions on the crystal structure and luminescence properties was explored.Under ultraviolet excitation,the down-conversion phosphors showed warm white,red-orange,orange,and green characteristic emissions,indicating that La₄Ti₃O₁₂ is an excellent luminescent material matrix.The LED devices are manufactured by combining the as-synthesized down-conversion phosphors with UV LED chips,and the resulting LED devices emitted multicolor emissions,revealing that the phosphors have the potential for applications in LEDs and optoelectronic devices.Under near-infrared 980 nm excitation,the up-conversion phosphors showed green,yellow-green,and blue characteristic emissions,and achieved excellent up-conversion performance.It is expected that this work may be of great significance to the design and preparation of perovskite-type rare earth luminescent materials.The Sr₃AlO₄F:Eu³⁺fiber material with uniform morphology and good dispersion was synthesized by electrospinning for the first time.The influence of morphology and size of the precursor and calcination conditions on the luminescence properties of the samples were studied.Sr₃AlO₄F:Eu³⁺was co-doped with the monovalent alkali metal cation M⁺(M=Li,Na,K,Cs)to maintain charge balance.The codoping of charge compensator Li⁺not only improved the luminescence properties of Sr₃AlO₄F:Eu³⁺but also exhibited the eminet thermal stability.The LED devices that were synthesized by combining UV LED chips with the phosphors can emit bright red light,indicating that the phosphors have potential applications in the field of photoelectric devices.A series of rare earth luminescent materials La₁₀W₂₂O₈₁:Ln³⁺(Ln=Dy,Sm,Tb,Eu,Dy/Eu,Tb/Eu)were synthesized by Pechini sol-gel method.The effects of calcination conditions on the crystallization and luminescence properties of the samples were studied in detail.Under UV excitation,the rare earth ions Dy³⁺,Sm³⁺and Tb³⁺doped phosphors emitted cold white,orange,and green light,respectively.Dy³⁺/Eu³⁺and Tb³⁺/Eu³⁺were co-doped into the La₁₀W₂₂O₈₁?The tunable luminescence including white light emission can be realized by changing the doping concentrations of Eu³⁺or adjusting the excitation wavelengths.The results show that the as prepared La₁₀W₂₂O₈₁:Ln³⁺(Ln=Dy,Sm,Tb)phosphors are promising to be applied in the field of optoelectronic devices,and the La₁₀W₂₂O₈₁:Dy³⁺/Eu³⁺and La₁₀W₂₂O₈₁:Tb³⁺/Eu³⁺single matrix white light-emitting materials have a good application prospect in field of WLEDs.