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
Nanosized long-persistent phosphors SrS：Eu^2＋, Dy^3＋ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device ...Nanosized long-persistent phosphors SrS：Eu^2＋, Dy^3＋ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry.The persistence characteristic was studied using the decay curves.The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased.The S2-vacancies caused by oxidization served as shallow traps, and Dy3＋ served as deep traps in SrS：Eu^2＋, Dy^3＋.The afterglow intensity of SrS：Eu^2＋, Dy^3＋ was higher than that of SrS：Eu2＋ prepared at the same temperature.However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter.Binary-doped phosphor decayed more slowly than the singly doped one.The afterglow of SrS：Eu^2＋, Dy^3＋ decayed more quickly with the increase of sintering temperature.展开更多
The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2+). According to the growth unit model, the growth units of lead tungst...The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2+). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.展开更多
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supported by the National Natural Science Foundation of China (10774012 and 10434030)Beijing Jiaotong University Program (2007XM048, 2006XM038)
文摘Nanosized long-persistent phosphors SrS：Eu^2＋, Dy^3＋ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry.The persistence characteristic was studied using the decay curves.The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased.The S2-vacancies caused by oxidization served as shallow traps, and Dy3＋ served as deep traps in SrS：Eu^2＋, Dy^3＋.The afterglow intensity of SrS：Eu^2＋, Dy^3＋ was higher than that of SrS：Eu2＋ prepared at the same temperature.However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter.Binary-doped phosphor decayed more slowly than the singly doped one.The afterglow of SrS：Eu^2＋, Dy^3＋ decayed more quickly with the increase of sintering temperature.
文摘The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2+). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.
