By using metal nitrates as starting materials and citric acid as a complexing agent, Y2Si207：Re3＋ （Re=Eu, Tb） phosphors were prepared by a sol-gel method. X-ray diffraction was employed to characterize the resulti...By using metal nitrates as starting materials and citric acid as a complexing agent, Y2Si207：Re3＋ （Re=Eu, Tb） phosphors were prepared by a sol-gel method. X-ray diffraction was employed to characterize the resulting samples. The results of XRD indicate that the α-Y2Si2O7 nanocrystal with size of 27 nm is obtained at 1000 ℃ and the doping ion content does not influence the structure. The excitation spectra in the UV and VUV ranges and the emission spectra of Re^3＋ doped samples were measured. The excitation spectra in the VUV range is due to absorption of host, that in the UV range is ascribed to absorption transitions from 4f to 5d state of the Tb^3＋ and the charge transfer in the En^3＋-O^2- bond. The spectral energy distribution of the Tb^3＋ emission depends strongly on the Tb3＋ concentration. The dependence of photolumineseenee intensity on Re^3＋ concentration is also discussed in detail. The fluorescent decay curves at room temperature were measured and analyzed.展开更多
Europium-doped yttrium aluminum garnet nanopowders were synthesized through an aqueous sol-gel method. The structure, morphology and luminescence spectra were investigated by using X-ray diffraction, thermogravimetric...Europium-doped yttrium aluminum garnet nanopowders were synthesized through an aqueous sol-gel method. The structure, morphology and luminescence spectra were investigated by using X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy measurements. The results show that YAG：Eu with an average particle size of 50 nm is formed. The activation energy of YAG：Eu nanocrystallite growth during calcination is 24.1 kJ/mol. The crystalline YAG：Eu nanopowders show an orange-red emission with 5D0–7F1 as the most prominent group.展开更多
文摘By using metal nitrates as starting materials and citric acid as a complexing agent, Y2Si207：Re3＋ （Re=Eu, Tb） phosphors were prepared by a sol-gel method. X-ray diffraction was employed to characterize the resulting samples. The results of XRD indicate that the α-Y2Si2O7 nanocrystal with size of 27 nm is obtained at 1000 ℃ and the doping ion content does not influence the structure. The excitation spectra in the UV and VUV ranges and the emission spectra of Re^3＋ doped samples were measured. The excitation spectra in the VUV range is due to absorption of host, that in the UV range is ascribed to absorption transitions from 4f to 5d state of the Tb^3＋ and the charge transfer in the En^3＋-O^2- bond. The spectral energy distribution of the Tb^3＋ emission depends strongly on the Tb3＋ concentration. The dependence of photolumineseenee intensity on Re^3＋ concentration is also discussed in detail. The fluorescent decay curves at room temperature were measured and analyzed.
基金Project supported by the Islamic Azad University,Najafabad Branch,Iran
文摘Europium-doped yttrium aluminum garnet nanopowders were synthesized through an aqueous sol-gel method. The structure, morphology and luminescence spectra were investigated by using X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy measurements. The results show that YAG：Eu with an average particle size of 50 nm is formed. The activation energy of YAG：Eu nanocrystallite growth during calcination is 24.1 kJ/mol. The crystalline YAG：Eu nanopowders show an orange-red emission with 5D0–7F1 as the most prominent group.
