Luminescence Properties And Application Of Rare Earth Ions Doped Aluminosilicate Phosphors

In the field of industrial and living lighting,the application of white light-emitting diode?WLED?is becoming more and more common.It has the advantages of energy conservation,environmental friendliness and not easily damaged.For WLED,rare earth doping phosphor is the most important part of it.At present,commercial WLED is mainly prepared by a method of mixing the yellow phosphor with blue chip.However,this white LED has a lower color rendering index,a higher color temperature and other defects.In order to avoid this kind of defect,we can use red,green and blue trichromatic phosphors to mix and form white light under ultraviolet chip excitation.However,there is photon reabsorption between different phosphors;and the stability of different phosphors is different;these disadvantages can affect the performance of white LEDs.T Therefore,the solution of realizing different colors of tunable emission light in a single host is expected to improve the stability and color rendering index of the materials.Aluminosilicate is often used as a substrate for phosphor because of its excellent thermodynamics,chemistry,mechanical stability and structural diversity.More and more attention has been paid to the research of rare earth doped aluminosilicate phosphors.In this dissertation,we mainly use aluminosilicate as the host,and the color can be adjusted by co-doping with different rare earth ions.At the same time,the crystal structure,energy transfer between ions,luminescent properties,thermal stability and practical applications of the phosphor have been studied in detail,including the following aspects:1.A series of emission-tunable Na_1-xAl_1+2xSi_1-2xO₄:xCe³⁺/Tb³⁺/Dy³⁺phosphors were synthesized via high temperature solid-state reaction method.The luminescence properties,energy transfer from Ce³⁺to Tb³⁺/Dy³⁺ions,color tuning and thermally stability were systematically investigated.The charge compensating defect generated by the doping of rare earth ions had been remedied through Al³⁺substituted Si⁴⁺.The presence and content of various elements had been demonstrated through the data combined with the crystallographic data from Rietveld refinements and the analysis of SEM and mapping for each element.The energy transfer mechanisms from Ce³⁺to Tb³⁺/Dy³⁺in the co-doped samples had been studied.Additionally,the temperature-dependent photoluminescence for as-prepared phosphors had been investigated in detail.2.A series of emission-tunable Ce³⁺/Tb³⁺/Eu²⁺doped Ca₂(Mg_0.75Al_0.25)(Si_1.75Al_0.25)O₇?denote as CMAS?phosphors were synthesized via high temperature solid-state reaction method.The luminescence properties,color tuning,QYs,energy transfer of Ce³⁺to Tb³⁺/Eu²⁺and performance of LED devices were systematically investigated respectively.And combined with the crystallographic data from Rietveld refinements,XRD,the analysis of SEM and mapping for each element,the crystal structure and element distribution were analyzed.The emission of sample particles under the excitation of 330-385 nm UV lamps was observed.The luminescence properties of Ce³⁺/Tb³⁺/Eu²⁺doped samples have been studied.The energy transfer of Ce³⁺to Tb³⁺/Eu²⁺and its effect on the luminescence properties were discussed.At the same time,the color adjustable properties of CMAS:xCe³⁺/yEu²⁺/zTb³⁺were discussed.3.Using the CMAS:Ce³⁺/Tb³⁺/Eu²⁺cold white phosphor synthesized in Chapter 3 mixing with commercially available red phosphor,the WLEDs device with warm white light emission was prepared.The influence of preparation and process on the performance of WLEDs devices was systematically studied.Through the electroluminescence test of WLEDs devices,the related application parameters of the series WLEDs devices were determined,including the color temperature and the color rendering index.In addition,the thermal stability of Ce³⁺and Tb³⁺/Eu²⁺co-doped samples was discussed through the study of temperature dependence spectra.At the same time,the CMAS:Ce³⁺,Eu²⁺samples were analyzed for temperature sensing,including temperature sensing range and sensitivity.