The Preparation,Morphology Control And Optical Properties Of Molybdate And Fluoride Fluorescent Materials Doped With Rare Earth Ions

Due to the unique property of the 4f shell electrons,rare earth ions can exhibit different electronic transition forms and extremely rich energy level transitions.Therefore,rare earth ions can absorb or emit light from ultraviolet to infrared wavelengths.The luminescent properties lay the foundation for the wide application of rare earth ions in luminescent materials.In recent years,rare earth luminescent materials have a wide range of applications in the fields of flat panel display,laser devices,sensing,and biological imaging and biological detection owing to its excellent luminescent properties,strong light absorption,stable chemical properties,long fluorescence lifetime,high color purity,high fluorescence efficiency,low energy consumption,and environmental friendliness.In general,the physical,chemical,and optical properties of rare earth luminescent materials are closely related to their chemical composition,morphology,size,and dimensions.Therefore,the controlled synthesis of micro-nano structures with high purity,uniform dispersion,morphology and size is of great significance for the performance control of rare earth luminescent materials.At the same time,it is of great significance to explore the influencing factors and basic growth mechanism of micro-nano crystal growth process for the synthesis of luminescent materials with specific morphology and size.Among the many synthetic methods,hydrothermal method is the simplest and most environmentally friendly synthesis method.This method not only has low synthesis cost,mild conditions,low energy consumption,but also produces samples of uniform size and dispersion.Meanwhile,the reaction conditions,such as initial solution pH,reaction temperature,time,additives are adjusted to synthesize samples of desired morphology and structure.The main contents of this article are as follows:?1?AgLa?MoO₄?₂ micro-nanocrystals with various morphologies and sizes were synthesized by hydrothermal method,and the experimental factors such as Mo/La molar ratio,pH value,surfactant and reaction time in the initial solution were changed.Crystals with different structures,morphologies and sizes were obtained,such as disc-shaped layered structures composed of nanosheets,nested structures,spherical spheroidal crystals and ellipsoidal crystals composed of nanoparticles,and the layered experiments were clarified by time experiments.At the same time,excellent up/down conversion luminescence is achieved by mono-doping or co-doping Tb³⁺,Eu³⁺,Sm³⁺,Dy³⁺,Yb³⁺-Er³⁺,Yb³⁺-Tm³⁺,Yb³⁺-Ho³⁺and other rare earth ions in the AgLa?MoO₄?₂ matrix.The optimal emission is achieved by adjusting the doping ratio of the rare earth ions.?2?We successfully prepared a series of BaMgF₄:Ce³⁺/Tb³⁺/Eu³⁺phosphors by a simple one-step hydrothermal method.The morphology and size of the BaMgF₄ crystals were adjusted by changing the original amount of NH₄F in the initial solution.The luminescence properties and luminescence mechanism were studied in detail,and the energy transfer of Ce³⁺?Tb³⁺,Tb³⁺?Eu³⁺was proved from many angles.By changing the relative doping ratios of Ce³⁺-Tb³⁺and Tb³⁺-Eu³⁺,different energy transfer efficiencies are obtained,and finally the regulation of luminescent color from blue light to green light,green light to yellow light,and then orange red light is realized.?3?A series of AgY?MoO₄?₂ phosphors co-doped with Yb³⁺-Er³⁺,Yb³⁺-Tm³⁺and Yb³⁺-Ho³⁺were successfully prepared by simple hydrothermal synthesis.The phase,morphology,upconversion luminescence properties and the temperature characteristics of AgY?MoO₄?₂ phosphor doped with Yb³⁺-Er³⁺were studied in detail.