The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and p...The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and photoluminescence spectra were employed to charac- terize its structure and morphology as well as luminescent properties. The results indicated that the red-emitting phosphor La2Zr207：Eu3＋ had well crystallized and belonged to the cubic structure with space group of Fd3m. The as-obtained product mainly appeared as straight nanorods with an average diameter of 47 nm and length of 50-700 nm. The pos- sible growth mechanism was also discussed. It was found that under blue excitation with a wavelength of 466 nm, the La2Zr2OT：Eu3＋ phosphor exhibited a characteristic red emission at 616 nm that was attributed to the hypersensitive 5D0--＊TF2 electric dipole transition of Eu3＋ ions. Meanwhile, it was more interesting to note that the emission of 5D1--＊TFj （J=0, 1, 2） transitions and the splitting patterns of 5D0---＋TFJ （J--l, 2, 4） transitions of Eu3＋ ions can be observed in the luminescent spectra of La2Zr207：Eu3＋. It was demonstrated that Eu3＋ preferred to occupy a low symmetry site.展开更多
A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission fro...A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission from Eu3＋. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3＋ to Dy3＋, which enhanced the emissions of Dy3＋. Combinations of the emissions from Eu3＋ and Dy3＋ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3＋ to Dy3＋ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.展开更多
文摘The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and photoluminescence spectra were employed to charac- terize its structure and morphology as well as luminescent properties. The results indicated that the red-emitting phosphor La2Zr207：Eu3＋ had well crystallized and belonged to the cubic structure with space group of Fd3m. The as-obtained product mainly appeared as straight nanorods with an average diameter of 47 nm and length of 50-700 nm. The pos- sible growth mechanism was also discussed. It was found that under blue excitation with a wavelength of 466 nm, the La2Zr2OT：Eu3＋ phosphor exhibited a characteristic red emission at 616 nm that was attributed to the hypersensitive 5D0--＊TF2 electric dipole transition of Eu3＋ ions. Meanwhile, it was more interesting to note that the emission of 5D1--＊TFj （J=0, 1, 2） transitions and the splitting patterns of 5D0---＋TFJ （J--l, 2, 4） transitions of Eu3＋ ions can be observed in the luminescent spectra of La2Zr207：Eu3＋. It was demonstrated that Eu3＋ preferred to occupy a low symmetry site.
基金supported by Fundamental Research Grant Scheme of Malaysia(J130000.2526.03H97)the National Natural Science Foundation of China(51372142)
文摘A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission from Eu3＋. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3＋ to Dy3＋, which enhanced the emissions of Dy3＋. Combinations of the emissions from Eu3＋ and Dy3＋ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3＋ to Dy3＋ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.
