| Rare earth element has good optical, electrical and magnetic properties, among which the optical is especially excellent and cannot be replaced, because of its unique electron shell structure. Therefore, in recent years, the study of Rare earth iron Eu3+and Tb3+are doped as activator to produce red and green fluorescent material is widely noted. Since luminescent property of activator is closely related to the doped matrix material, changing its matrix material is an important way to study rare earth luminescent material. This paper adopts the sol-gel method, taking La(NO3)3·6H2O,(NH4)2HPO4, Ethyl silicate, and Tetrabutyl titunate as raw material to make a matrix composited of LaPO4-5SiO2,LaPO4-7TiO2,and LaPO4-5SiO2-7TiO2, and then doping Eu3+or Tb3+, to produce rare earth luminescent materials. Use TG-DTA, TEM, XRD, IR and excitation and emission spectra, to characterize and analyze the nature of the morphology, structure, luminous material properties and then study the effect of the material structure, annealing temperature, doping concentration on light-emitting material performance. This study consists of two parts: Part one:Rare earth element both is Eu3+ions. Select LaPO4-5SiO2, LaPO4-7TiO2, LaPO4-5SiO2-7TiO2as the composite matrix. The experimental results show that the Eu3+doped with LaPO4-5SiO2, LaPO4-7TiO2, LaPO4-5SiO2-7TiO2three kinds of rare earth luminescent material, can emit red light with good monochromaticity and bigger intensity. All of them are good red light-emitting materials, of which LaPO4-7TiO2doped Eu3+ion luminescence performance are the most excellent.In the study of LaPO4-5SiO2as the matrix of luminescent material to compare the luminescence properties of pure LaPO4, SiO2and compound matrix LaPO4-5SiO2, it found that the composite substrate material is more advantageous to dope with Eu3+and its luminous property is more excellent, and also it can save more rare earths. The best annealing temperature of LaPO4-5SiO2:Eu3+luminescence materials is800℃. Meanwhile, its structure is mainly LaPO4six-party phase, and it largely exists in keys of Si-O-Si and P-O-P. The optimum excitation wavelength of LaPO4-5SiO2:Eu3+is395nm. Its Eu3+doping density is from7.00%to9.00%(at%) and simultaneously the luminous intensity of material basic consistent keeps the same. All of those reduce the difficulty in preparation and application of the material. In the LaPO4-7TiO2:Eu3+luminescence materials, the optimum excitation wavelength is465nm, and the optimal doping concentration of Eu3+is9.00%(at%). In400℃annealing treatment, the material forms amorphous state, while in1000℃annealing treatment it forms crystalline state. No matter in the amorphous or crystalline state, the luminous intensity of the material all is big. Comparatively speaking, it is bigger in crystalline state. In LaPO4-5SiO2-7TiO2:Eu3+luminescent material, its optimum excitation wavelength is also465nm, and its best annealing temperature is800℃. At this moment, the material is in the defect mode, which is very conducive to the doping of Eu3+into matrix materials to improve its luminous intensity. Meanwhile, infrared spectrum and emission spectrum analysis show that the formation of Ti-O-Si key destroys the Ti-O-Ti key in the material, changes the network structure of TiO2, and influences its symmetry, and the change in symmetry greatly affects the luminescence properties of Eu3+.Comparing three kinds of synthetic rare earth luminescent material Eu3+doped respectively with LaPO4-5SiO2, LaPO4-7TiO2and LaPO4-5SiO2-7TiO2, it finds that the light performance of the first one is the most excellent. Its electric dipole transition launch is far higher than that of magnetic dipole transition, so its monochromaticity is better. At the same time when the doping amount of Eu3+ions is9.00%(at%)(At this point the luminous intensity of three kinds of luminous materials basically reaches their maximum luminous intensity), the luminous intensity of LaPO4-7TiO2is greater than that of the other two materials. So the light performance of Eu3+ions doped LaPO4-7TiO2is the most excellent. Part two:Select LaPO4-5SiO2as matrix material for the preparation of green light-emitting materials only with Tb3+and white light emitting materials with Eu3+, Tb3+.The experimental results show that the former, which can emit green light, is a good green luminescent material while the latter which can emit in three wavebands, red, green and blue, can be made into white light emitting materials. In the luminescent material of Tb3+single doped with LaPO4-5SiO2, its best annealing temperature is800℃, and its optimum excitation wavelength is377nm. When the doping of Tb3+concentration is from7.00%to10.00%(at%), its emission intensity basically remains stable. When doped together, Tb3+can sensitize Eu3+. In the LaPO4-5SiO2luminescent material doped with Eu3+and Tb3+, the balance of Eu3+(4f6)+Tb3+(4f8)=Eu2+(4f7)+Tb4+(4f7), leads the material to emit blue light of Eu2+, green light of Tb3+and red light of Eu3+, so that by adjusting the proportion of doped rare earth ions, it can produce the synthesis the white light emitting materials. To sum up, LaPO4-5SiO2doped only with Tb3+or co-doped with Eu3+and Tb3+can emit a better green light or white light. Considering its fine thermal stability, fixed crystal structured obtained after high temperature annealing, low cost and easy access, LaP04-5SiO2is an excellent preparation substrate material to produce luminescent material. |
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