Photoluminescence Charater Of Rare Earth (Pr³⁺,Sm³⁺,Er³⁺,Yb³⁺)Co-doped Al₂O₃

Rare earth doped luminescence materials can not only play an important role in lighting field, but also play an irreplaceable role on environmental, energy, medical, military, and so on.Firstly, Pr³⁺-doped, Pr³⁺/Yb³⁺ co-doped and Pr³⁺/Yb³⁺/Ag+ co-doped Al₂O₃ powder, and Sm³⁺-doped, Sm³⁺/Yb³⁺/Er³⁺ co-doped Al₂O₃ powder have been prepared by nonaqueous sol-gel method. The fluorescence properties of samples were represented by excitation spectra, emission spectra, X-ray diffraction (XRD) and up-conversion fluorescence spectra. The energy transfer mechanisms were discussed, and the influence of samples concentrations on fluorescence intensity were analyzed. According to Pr³⁺-doped Al₂O₃ powder samples XRD spectra, the effect on phase composition around Al₂O₃ host material with Pr³⁺ dopant was studied, and the phase composition figure of Pr³⁺-doped Al₂O₃ powder was established at 1000℃sintering temperature. The results show thatγ-Al₂O₃ phase andθ-Al₂O₃ phase were in the samples, and the diffraction peak intensity weakens with the increase of doping concentration.Then the excitation spectra and the emission spectra of Pr³⁺-doped and Pr³⁺/Yb³⁺ co-doped Al₂O₃ powder samples were measured. When monitoring the 657 nm characteristics emission of Pr³⁺ ions, the best 540 nm excitation wavelength was got, and the absorption transition excitation peak of Al₂O₃ host was observed at 280 nm. When exciting samples with 376 426 and 540 nm different wavelengths, the blue green and red emission of Pr³⁺ ions were obtained respectively at 468 540 and 655 nm, and the influence of the excitation spectra and emission spectra under different Pr³⁺/Yb³⁺ doping concentration was discussed. The results show that the Yb³⁺ dopant play the sensitization role in the luminescence of Pr³⁺ ions.Thirdly, the up-conversion mechanism of Pr³⁺/Yb³⁺ co-doped and Pr³⁺/Yb³⁺/Ag+ co-doped samples were discussed. Pr³⁺/Yb³⁺ co-doped Al₂O₃ powder samples have the up-conversion luminous characteristics that the emission wavelengths are 410 490 525 546 and 658 nm. The up-conversion fluorescence intensity of Pr³⁺-doped Al₂O₃ powder samples was enhanced with Yb³⁺ co-doped, when the concentration of Pr³⁺ ions and Yb³⁺ ions are 0.1 mol% and 1 mol%, the result is optimal. Yb³⁺ ions not only play the sensitization role of Pr³⁺ ions, but also exist Pr³⁺ ions to Yb³⁺ ions reverse energy transfer process when Yb³⁺ ions doping concentration is low. The introduction of heavy metal silver led to the reduction of 3P1 level life of Pr³⁺ ions, but an increases of 3P0 level life which made the fluorescence intensity of 551 nm (3P0â†'3H5) of Pr³⁺ ions stronger than the fluorescence intensity of 527 nm (3P1â†'3H5).At last, Sm³⁺-doped and Sm³⁺/Yb³⁺/Er³⁺ co-doped Al₂O₃ powder samples were analyzed. According to excitation spectra and emission spectra, when samples were excited by 402 nm, to 602 nm emission is the most advantageous. The reasons for causing Sm³⁺ concentration quenching was discussed. The samples of the up-conversion fluorescence spectra under 980 nm pump light were measured, the up-conversion of the main emission peaks was discussed, it turned out that Er³⁺ ions and Yb³⁺ ions dopant enhance up-conversion fluorescence intensity at 658 nm, the energy transfer mode is Sm³⁺ ionsâ†'Yb³⁺ ionsâ†'Er³⁺ ions. The out of analyzing the relations up-conversion fluorescence intensity between different pump power indicates that up-conversion fluorescence is two photons progress at 525, 547 and 685 nm.