Synthesis And Luminescence Properties Of New Perovskite Phosphor

White light emitting diodes（WLED）based on rare earth doped fluorescent materials have become a new generation of solid-state lighting sources due to their excellent luminous performance,long life,low energy consumption,environmental protection,etc.In this paper,the crystal structure and luminescent properties of phosphors doped with one or two rare earth ions using perovskite type indium salts as the substrate were prepared and studied.The correlation between process parameters and the properties of phosphors was analyzed,and the luminescent mechanisms were revealed.The work in this paper provides a certain material foundation and theoretical support for the research and development of new stable and high luminous efficiency phosphors,as well as the improvement of the luminous performance of WLED devices.The specific content is as follows:（1）A series of SrIn_1.95-xO₄:0.05Eu³⁺,x Y³⁺red phosphors were prepared by high-temperature solid-state method at 1400℃.The phase structure and surface morphology of the sample were analyzed through XRD and SEM.The Rietveld refinement of XRD shows that Eu³⁺and Y³⁺ions substituted for In³⁺ions lattice sites.Diffuse reflectance spectrum shows that the band gap of the matrix decreases from 3.60 e V to 3.41 e V.The optimum excitation wavelength of phosphor is 308 nm after doping with Y³⁺,and the intensity of red light emitted is three times that of the original SrIn_1.95O₄:0.05Eu³⁺phosphor when Y³⁺ions doping concentration reaches 0.1.The concentration quenching effect occurs when the concentration of Y³⁺ions is greater than 0.1,which is caused by the quadrupole-quadrupole interaction between the emission centers.In addition,SrIn_1.85O₄:0.05Eu³⁺,0.1Y³⁺phosphors have good thermal stability（activation energy 0.216 e V）and long fluorescence lifetime（0.72 ms）,and the chromaticity coordinate of（0.633,0.315）is also very close to commercial red phosphors.（2）A new matrix SrYInO₄ and SrY_1-xInO₄:xEu³⁺red phosphors were prepared by high-temperature solid-state method.The phase,morphology and composition of the samples were studied based on XRD,and XRD Rietveld refinement,SEM,and EDS.The UV-visible diffuse reflectance spectrum shows that the band gap of SrYInO₄ increases to 4.08 e V compared to SrIn₂O₄,while the band gap of SrY_0.8InO₄:0.2Eu³⁺phosphor decreases to 3.63 e V.Excited by308 nm,SrY_0.8InO₄:0.2Eu³⁺phosphor emits bright orange light with the main emission peak located at 617 nm.Concentration quenching effect occurs when the concentration of Eu³⁺ions exceeds 0.2,and the quadrupole-quadrupole interaction is the main reason for its concentration quenching.In addition,SrY_0.8InO₄:0.2Eu³⁺phosphor has excellent thermal stability,and the fluorescence lifetime reaches microsecond level（1.37 ms）.The color coordinate of（0.637,0.323）is located in the red region.（3）A series of SrY_1-xInO₄:x Er³⁺green phosphors were synthesized via high-temperature solid-state method.XRD,SEM and EDS were used to study the phase structure and morphology of the samples.Diffuse reflectance spectrum shows that the band gap value of the matrix SrY_0.99InO₄:0.01Er³⁺phosphor decreases to 3.98 e V compared to SrYInO₄.Under the excitation of 380 nm,the phosphor emits 553 nm green light.When the doping concentration of Er³⁺is 0.01,the luminous intensity reaches the maximum.Concentration quenching effect occurs when the doping concentration is greater than 0.01,which is caused by the interaction between adjacent ions.The fluorescence lifetime of SrY_0.99InO₄:0.01Er³⁺phosphor is 87.46μs.The thermal quenching activation energy is 0.193 e V,and the chromaticity coordinates are located in the green region.（4）Based on the above work,a series of SrY_0.99-xInO₄:0.01Er³⁺,xEu³⁺double-doped phosphors were synthesized via high-temperature solid-state method.XRD,SEM,and EDS show that Eu³⁺and Er³⁺ions were successfully doped into the matrix,and the band gap decreased to 3.93 e V compared to SrYInO₄.Due to the energy transfer between Er³⁺ions and Eu³⁺ions,with the increase of Eu³⁺ions doping concentration,the color of phosphor changes from green to red under 380 nm ultraviolet excitation;Under the excitation of 308 nm,the luminescence changes from yellow to orange,thereby realizing the red green adjustment of the phosphor.