Study On The Lattice Occupancy And Spectral Characteristics Of Double Perovskite Phosphors

Phosphors are an indispensable part of white LEDs,and the development of phosphors with excellent performance has become the goal of many researchers.A2 B ’B "O6 type perovskite oxide have rich information on structure regulation.Through B site substitution and doping with rare earth or transition metal ions,it can produce a variety of interesting properties and possible applications,and has become a hot research in luminescent materials.In this paper,several A2B’B" O6 double perovskite structure phosphors were prepared by B site substitution,and then the luminescence characteristics were studied.The details are as follows:(1)La2Mg1-x/2Zr1-x/2O6:xBi3+and La2-yMg0.99Zr0.99O6:0.02Bi3+,yEu3+perovskite phosphors were prepared by traditional high-temperature solid-phase method.Through spectral analysis of La2Mg1-x/2Zr1-x/2O6:xBi3+,combined with Gaussian peaks and fluorescence decay lifetime tests,it is determined that there are two luminescence centers in La2Mg1-x/2Zr-x/2O6:xBi3+;Through the excitation of different excitation wavelengths(300~370nm),it is further verified that there are two emission centers in La2Mgx/2Zrx/2O6:xBi3+.On this basis,by adjusting the spectral range of Bi3+/Eu3+,the fluorescence spectrum characteristics of La2-yMg0.99Zr0.99O6:0.02Bi3+,yEu3+phosphors,the fluorescence lifetime and the energy conversion of Bi3+→Eu3+are studied.Achieve adjustable emission from green to red.(2)La2MgZr1-xO6:0.02Bi3+,xSn4+perovskite phosphors are prepared by traditional high-temperature solid-phase method.Through structural refinement analysis,selective occupancy of Bi3+occurs after Sn4+doping(x>0),and the fluorescence spectrum and fluorescence lifetime are tested and analyzed to further verify that the occupancy of Bi3+has changed.Through XRD and Rietveld refined analysis,combined with the bond energy method,the priority occupancy of Bi3+ions in the LMZ matrix was determined.Combined with Van Uitert’s empirical formula and energy level splitting theory,the emission peaks corresponding to the emission centers of Bi(Ⅰ),Bi(Ⅱ)and Bi(Ⅲ)in the spectrum are determined.(3)La2-xMgSnO6:xBi3+and La1.98MgSn1-yO6:0.02Bi3+,yMn4+series perovskite phosphors were prepared by traditional high-temperature solid-phase synthesis.Analyze the crystal structure information,fluorescence spectrum,and attenuation life structure performance characteristics of this series of phosphors,On the basis of La2-xMgSnO6:xBi3+,the Sn4+site is replaced by Mn4+,and the fluorescence spectrum and fluorescence lifetime are analyzed with the energy conversion of Bi3+→Mn4+,and the La1.98MgSn1-yO6:0.02Bi3+,yMn4+phosphor is adjustable from blue to red emission.