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
This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a ...This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a function of the temperature and frequency. The γ-Y2Si2O7 exhibits low dielectric loss and non-Debye relaxation behaviour from 25 to 1400℃ in the range of 7.3 18 GHz. The mechanism for polarization relaxation of the as-prepared γ-Y2Si2O7 differing from that of SiO2 is explained. Such particular dielectric properties could potentially make specific attraction for extensive practical applications.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 National Natural Science Foundation of China (Grant No. 50872159)the National Defense Pre-research Foundation of China (Grant Nos. 513180303 and A2220061080)
文摘This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a function of the temperature and frequency. The γ-Y2Si2O7 exhibits low dielectric loss and non-Debye relaxation behaviour from 25 to 1400℃ in the range of 7.3 18 GHz. The mechanism for polarization relaxation of the as-prepared γ-Y2Si2O7 differing from that of SiO2 is explained. Such particular dielectric properties could potentially make specific attraction for extensive practical applications.
