The Synthesis And Luminescent Properties Of Rare-earth Doped Framework Silicate Phosphors On Kaolin

The deep processing technology of kaolin resources and the transformation of functional materials are the research directions of comprehensive utilization of kaolin resources.Rare earth doped framework based silicate based fluorescent materials have excellent luminescent properties.Nepheline and sodium aragonite have larger ion channels and stable crystal field environment.They are ideal materials for preparing rare earth fluorescent materials.In this paper,kaolinite is used as the raw material to synthesize nepheline with high temperature solid phase method and the synthesis of Alinite under the condition of hydrothermal and atmospheric pressure.The crystal phase composition and microstructure of the products are analyzed by X ray diffractometer and field emission scanning electron microscope,and the optimum conditions for the synthesis of potassium nepheline and Alinite from kaolin are determined and analyzed.On the basis of the reaction mechanism,rare earth doped nepheline and sodium sodium phosphor were prepared,and their spectral properties were analyzed by fluorescence spectrometer,and their luminescence properties and influencing factors were studied.The conclusions are as follows:?1?The contrast found that the luminescence intensity of NaAlSiO₄:1%Eu³⁺under the same condition is far lower than that of KAlSiO₄:1%Eu³⁺.Compared with other potash salts,K₂CO₃ is the best raw material for the synthesis of potassium nepheline by high temperature solid phase method.The effect of material composition and sintering system on the synthesis of potassium nepheline is investigated respectively.The result shows that the proportion of material is nK₂CO₃/n?kaolin?=1.2,and the sintering system is made.Potassium potassium nepheline is the best synthesized when the temperature is 1000?-2h.The Eu³⁺doped KAlSiO₄ fluorescent material was prepared.The optimum doping concentration of Eu³⁺was5%,which could be effectively stimulated by 466nm blue light and the emission of red light with a wavelength of 616nm can be used as the red phosphor excited by the blue light chip.Y³⁺,La³⁺,B³⁺and Eu³⁺Co doped KAlSiO₄ fluorescent materials were prepared respectively.It was found that Y³⁺was sensitized to the luminescent center of Eu³⁺.The doping of La³⁺causes the matrix lattice defects to be too large and lead to the quenching of the luminescence.The products doped with B³⁺are amorphous structure,the position of the strongest emission peak is changed from 466nm to 396nm,the emission peak is not obviously offset,it is still located at 616nm and is red light emission,and the preparation of KAlSiO₄:5%Tb³⁺fluorescent material is found to be the main excitation.The peak is excited by 488nm blue light,and the green light at 547nm wavelength is emitted.?2?Compared with normal pressure heating conditions,the crystalline integrity,particle uniformity and dispersion of the synthesized albium under hydrothermal conditions are better,and have high thermal stability.The optimum conditions for the synthesis of sodium alinate are MK:NaCl=2.3:5,NaOH concentration is 10mol/L,and the optimum reaction temperature is 110?under the condition of liquid to solid ratio 4:1 and alkali solution temperature of45?.The optimum crystallization time is 12h.The results show that the best concentration of Eu³⁺doped Na₈?AlSiO₄?₆?Cl?₂ fluorescent material is 7%,which can be effectively excited by near ultraviolet light with the wavelength of 396nm,and the strongest emission at 617nm.It is a potential application value red fluorescent material.Na₈?AlSiO₄?₆?Cl?₂:5%Tb³⁺is 7%.Under UV excitation,the strongest emission peak is located at 547nm.