A series of LiY1-xEux（MoO4）2 red-emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray diffraction （XRD） and photo-luminescence （PL...A series of LiY1-xEux（MoO4）2 red-emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray diffraction （XRD） and photo-luminescence （PL） spectra respectively. The effect of Eu3＋ doping concentration, annealing temperature and the molar ratio of citric acid to the total metal cations （C：M） on the optical properties of the red phosphors were studied and optimized. It was found that all the samples could be excited efficiently by blue light （465 nm）, which was well coincident with the emission of GaN based LED chips. The luminescent intensity reached maximum when annealing temperature was 750 ℃ and Eu3＋ doping concentration was 5% with C：M=3：1.展开更多
Praseodymium doped lithium yttrium molybdate Li Y1-8x Pr x（Mo O4）2（x=0.005-0.025） phosphors were successfully prepared by the hydrothermal method. The phase, morphology, and luminescent property of the prepared ph...Praseodymium doped lithium yttrium molybdate Li Y1-8x Pr x（Mo O4）2（x=0.005-0.025） phosphors were successfully prepared by the hydrothermal method. The phase, morphology, and luminescent property of the prepared phosphors were investigated by X-ray diffraction and scanning electron microscopy. The results indicated that doping of Pr^3＋ ions did not change the main phase of the phosphors. The samples emitted red luminescence upon excitation at 453 nm and the strongest emission peak corresponding to the characteristic transition of the Pr3＋ ion： 3P0→3F2 was observed at 657 nm. Li Y（Mo O4）2：Pr^3＋ red phosphors could be effectively excited by blue light emitting-diodes to emit red light; thus, acting as potential candidates for compensating the red light deficiency of cerium doped yttrium aluminum garnet yellow phosphor.展开更多
The Bi3＋ doped molybdate-based red-emitting phosphors, LiEu1-xBix（MoO4）2, were successfully synthesized with a sol-gel method. The prepared LiEu1-xBix（MoO4）2 phosphors exhibited pure and intense red emission at 6...The Bi3＋ doped molybdate-based red-emitting phosphors, LiEu1-xBix（MoO4）2, were successfully synthesized with a sol-gel method. The prepared LiEu1-xBix（MoO4）2 phosphors exhibited pure and intense red emission at 613 nm under the excitation of near-UV 394 nm. It was discussed in detail that the influence of the synthesis conditions such as the doping concentration of Bi3, the dose of citric acid, pH of the precursor solution and the sintering temperature on the emission intensity of the phosphors. According to the results, the optimal condition was obtained： the doping concentration of Bi3＋ was 15 mol.%, molar ratio of citric acid to metal ions was 1.5：1, pH of the precursor solution was 1.0 and the sintering temperature was 800 ℃. The X-ray diffraction （XRD） patterns of the LiEuo.85Bi0.15（MoO4）2 phosphor prepared under the optimal condition indicated that the phosphor was single phase with tetragonal scheelite structure. The Commission Intemationale de I＇E- clairage （CIE） chromaticity coordinates of LiEuo.85Bio.15（MoO4）2 were （x=0.655, y=0.345）, which were closer to the national television stan- dard committee （NTSC） standard values （x=0.670, y=0.330） than that of a commercial red phosphor of Y202S：Eu3＋（x=0.630, y=0.350）. This LiEuo.85Bi0As（MoO4）2 red phosphor is a promising candidate for the fabrication of white light-emitting diode （W-LED） with near-UV chips.展开更多
A series of novel red-emitting phosphors scheelite-like triple molybdates LiKGd2.xEux（MoO4）4（0.1≤ x ≤ 1.9） were synthesized by solid state reaction method and their photoluminescence properties were investigated...A series of novel red-emitting phosphors scheelite-like triple molybdates LiKGd2.xEux（MoO4）4（0.1≤ x ≤ 1.9） were synthesized by solid state reaction method and their photoluminescence properties were investigated. The photoluminescence results show that all samples can be excited efficiently by UV （396 nm） light and blue （466 nm） light and emit red （615 nm） light with line spectra, which are coupled well with the characteristic emission from UV-LED and blue LED, respectively. The experimental results and their analysis suggest that the energy transfer occurs due to dipole-dipole interactions among Eu3＋ ions in LiKGd2-xEux（MoO4）4. Compared with Cao.8MoO4： Eu0.2^3-, the emission intensity of LiKGdo.9（MoO4）4： Eu1.1^3- is about 1.4 times higher and the CIE chromaticity coordinates are as close to the National Television System Committee （NTSC） standard values as those of Cao.8MoO4： Eu0.2^3-. The optical properties suggest that LiKGdo.9（MoO4）4： Eu1.1^3- is an efficient red-emitting phosphor for white LEDs applications.展开更多
基金Project supported by National Natural Science Foundation of China (20903123)Key Project of Chinese Ministry of Education (211154)Natural Science Foundation Project of Chongqing (CSTC2010BA4009, KJTD201016 and CSTCjjA50006)
文摘A series of LiY1-xEux（MoO4）2 red-emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray diffraction （XRD） and photo-luminescence （PL） spectra respectively. The effect of Eu3＋ doping concentration, annealing temperature and the molar ratio of citric acid to the total metal cations （C：M） on the optical properties of the red phosphors were studied and optimized. It was found that all the samples could be excited efficiently by blue light （465 nm）, which was well coincident with the emission of GaN based LED chips. The luminescent intensity reached maximum when annealing temperature was 750 ℃ and Eu3＋ doping concentration was 5% with C：M=3：1.
基金supported by National Natural Science Foundation of China(21205092)the National High-tech Research and Development Program of China(863 Program)(2011AA05A202)
文摘Praseodymium doped lithium yttrium molybdate Li Y1-8x Pr x（Mo O4）2（x=0.005-0.025） phosphors were successfully prepared by the hydrothermal method. The phase, morphology, and luminescent property of the prepared phosphors were investigated by X-ray diffraction and scanning electron microscopy. The results indicated that doping of Pr^3＋ ions did not change the main phase of the phosphors. The samples emitted red luminescence upon excitation at 453 nm and the strongest emission peak corresponding to the characteristic transition of the Pr3＋ ion： 3P0→3F2 was observed at 657 nm. Li Y（Mo O4）2：Pr^3＋ red phosphors could be effectively excited by blue light emitting-diodes to emit red light; thus, acting as potential candidates for compensating the red light deficiency of cerium doped yttrium aluminum garnet yellow phosphor.
基金Project supported by National Natural Science Foundation of China (NSFC20803097, NSFC20603049)Natural Science Foundation of Chongqing (CSTC2011AB4056, CSTC2009BA4023)the Fundamental Research Funds for the Central Universities (CDJZR10220005 and CDJRC10220002)
文摘The Bi3＋ doped molybdate-based red-emitting phosphors, LiEu1-xBix（MoO4）2, were successfully synthesized with a sol-gel method. The prepared LiEu1-xBix（MoO4）2 phosphors exhibited pure and intense red emission at 613 nm under the excitation of near-UV 394 nm. It was discussed in detail that the influence of the synthesis conditions such as the doping concentration of Bi3, the dose of citric acid, pH of the precursor solution and the sintering temperature on the emission intensity of the phosphors. According to the results, the optimal condition was obtained： the doping concentration of Bi3＋ was 15 mol.%, molar ratio of citric acid to metal ions was 1.5：1, pH of the precursor solution was 1.0 and the sintering temperature was 800 ℃. The X-ray diffraction （XRD） patterns of the LiEuo.85Bi0.15（MoO4）2 phosphor prepared under the optimal condition indicated that the phosphor was single phase with tetragonal scheelite structure. The Commission Intemationale de I＇E- clairage （CIE） chromaticity coordinates of LiEuo.85Bio.15（MoO4）2 were （x=0.655, y=0.345）, which were closer to the national television stan- dard committee （NTSC） standard values （x=0.670, y=0.330） than that of a commercial red phosphor of Y202S：Eu3＋（x=0.630, y=0.350）. This LiEuo.85Bi0As（MoO4）2 red phosphor is a promising candidate for the fabrication of white light-emitting diode （W-LED） with near-UV chips.
基金supported by the Major Science and Technology Projects of Wuhan City Science and Technology Bureau (Grant No.200810321148)
文摘A series of novel red-emitting phosphors scheelite-like triple molybdates LiKGd2.xEux（MoO4）4（0.1≤ x ≤ 1.9） were synthesized by solid state reaction method and their photoluminescence properties were investigated. The photoluminescence results show that all samples can be excited efficiently by UV （396 nm） light and blue （466 nm） light and emit red （615 nm） light with line spectra, which are coupled well with the characteristic emission from UV-LED and blue LED, respectively. The experimental results and their analysis suggest that the energy transfer occurs due to dipole-dipole interactions among Eu3＋ ions in LiKGd2-xEux（MoO4）4. Compared with Cao.8MoO4： Eu0.2^3-, the emission intensity of LiKGdo.9（MoO4）4： Eu1.1^3- is about 1.4 times higher and the CIE chromaticity coordinates are as close to the National Television System Committee （NTSC） standard values as those of Cao.8MoO4： Eu0.2^3-. The optical properties suggest that LiKGdo.9（MoO4）4： Eu1.1^3- is an efficient red-emitting phosphor for white LEDs applications.
