A single-phased silicate compound （Ba1-xCex）9（Sc1-yMny）2Si6O24 was prepared by solid-state reaction at high temperature. From powder X-ray diffraction （XRD） analysis, the formation of Ba9Sc2Si6O24 with an R3 spa...A single-phased silicate compound （Ba1-xCex）9（Sc1-yMny）2Si6O24 was prepared by solid-state reaction at high temperature. From powder X-ray diffraction （XRD） analysis, the formation of Ba9Sc2Si6O24 with an R3 space group was confirmed. In the photoluminescence spectra under ultraviolet （UV） ray excitation, the Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor emits two distinctive color light bands： a blue one originating from Ce3＋and a red one caused by Mn2＋. The energy transfer process from Ce3＋ to Mn2＋ was confirmed, the critical radius as well as the transfer efficiency was calculated, and the energy transfer mechanism was discussed. In addition, the decay-time testing indicates that the energy transfer efficiencies from Ce（1） to Mn2＋ and Ce（2） to Mn2＋ are different. The emission chromaticity of Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor could be tuned from blue to red by altering the Ce3＋/Mn2＋ concentration ratio.展开更多
Li 2+ x RE x Si 1- x O 3(RE=Pr, Nd, Sm, Gd; x =0～0 15) samples were prepared by the sol gel method. DTA TG, XRD, TEM and A C impedance techniques were used to investigate the structure, sha...Li 2+ x RE x Si 1- x O 3(RE=Pr, Nd, Sm, Gd; x =0～0 15) samples were prepared by the sol gel method. DTA TG, XRD, TEM and A C impedance techniques were used to investigate the structure, shape, and ionic conductivity of these samples. The results show that the range of solid solution formation is in 0< x ≤0 09, in which the conductivity of these samples raises with the increasing amount of RE 2O 3 (RE=Pr, Nd, Sm, Gd) added, and the diameter of the powders is about 100 nm. Compared with the conventional solid state reaction, the sol gel method needs low temperature and presents high ionic conductivity.展开更多
A series of Tb^3＋ mono-doped and Ce^3＋-Tb^3＋ co-doped Sr3Gd2（Si3O9）2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2（Si3O9...A series of Tb^3＋ mono-doped and Ce^3＋-Tb^3＋ co-doped Sr3Gd2（Si3O9）2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2（Si3O9）2：Tb^3＋ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ（J=6, 5, 4, 3） of Tb^3＋ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3＋ rose steadily in Sr3Gd2（Si3O9）2 host with the increase of Tb^3＋ concentration even though Gd^3＋ ions were completely replaced by Tb^3＋ ions. The Ce^3＋ ion as a sensitizer could efficiently improve the performance of Tb^3＋ ion. First, with Ce^3＋ co-doping, the excitation spectrum of Tb^3＋ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3＋ monitored at 416 nm. Second, the quantum yields of Sr3Gd2（Si3O9）2：Tb^3＋ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3＋. Finally, the co-doping of Ce^3＋ was also effective to improve the thermal stability of Sr3Gd2（Si3O9）2：Tb^3＋. As the temperature rose to 150 oC, the emission intensity of Tb^3＋ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG：Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2（Si3O9）2：Tb^3＋,Ce^3＋ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.展开更多
The strong yellow upconversion （UC） light emission was observed in Ho3＋/yb3＋ co-doped Gd2M0309 phosphor under the excitation of 980 nm diode laser. The phosphors were synthesized by the traditional solid-state rea...The strong yellow upconversion （UC） light emission was observed in Ho3＋/yb3＋ co-doped Gd2M0309 phosphor under the excitation of 980 nm diode laser. The phosphors were synthesized by the traditional solid-state reaction method. The structures of the samples were characterized by X-ray diffraction （XRD）. Under 980 nm excitation, Ho3＋/yb3＋ co-doped Gd2Mo3O9 exhibited strong yellow UC emission based on the green emission near 541 nm generated by 5F4,5S2→5i8 transition and the strong red emission around 660 nm generated by 5F5→5I8 transition, which assigned to the intra-4f transitions of Ho3＋ ions. The doping concentrations of Ho3＋ and Yb3＋ were determined to be 0.01 mol Ho3＋ and 0.2 mol Yb3＋ for the strongest yellow emission. Then the dependence of UC emis- sion intensity on excitation power density showed that the green and red UC emissions were involved in two-photon process. The possible UC mechanisms for the strong yellow emission were also investigated. The result indicated that this material was a promis- ing candidate for the application in the yellow display field.展开更多
基金the National Natural Science Foundation of China(Grant No.51272027)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20100006110011)
文摘A single-phased silicate compound （Ba1-xCex）9（Sc1-yMny）2Si6O24 was prepared by solid-state reaction at high temperature. From powder X-ray diffraction （XRD） analysis, the formation of Ba9Sc2Si6O24 with an R3 space group was confirmed. In the photoluminescence spectra under ultraviolet （UV） ray excitation, the Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor emits two distinctive color light bands： a blue one originating from Ce3＋and a red one caused by Mn2＋. The energy transfer process from Ce3＋ to Mn2＋ was confirmed, the critical radius as well as the transfer efficiency was calculated, and the energy transfer mechanism was discussed. In addition, the decay-time testing indicates that the energy transfer efficiencies from Ce（1） to Mn2＋ and Ce（2） to Mn2＋ are different. The emission chromaticity of Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor could be tuned from blue to red by altering the Ce3＋/Mn2＋ concentration ratio.
文摘Li 2+ x RE x Si 1- x O 3(RE=Pr, Nd, Sm, Gd; x =0～0 15) samples were prepared by the sol gel method. DTA TG, XRD, TEM and A C impedance techniques were used to investigate the structure, shape, and ionic conductivity of these samples. The results show that the range of solid solution formation is in 0< x ≤0 09, in which the conductivity of these samples raises with the increasing amount of RE 2O 3 (RE=Pr, Nd, Sm, Gd) added, and the diameter of the powders is about 100 nm. Compared with the conventional solid state reaction, the sol gel method needs low temperature and presents high ionic conductivity.
基金Project supported by National Natural Science Foundation of China(21571162)the Guangdong Province Enterprise-University-Academy Collaborative Project(2012B091100474)
文摘A series of Tb^3＋ mono-doped and Ce^3＋-Tb^3＋ co-doped Sr3Gd2（Si3O9）2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2（Si3O9）2：Tb^3＋ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ（J=6, 5, 4, 3） of Tb^3＋ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3＋ rose steadily in Sr3Gd2（Si3O9）2 host with the increase of Tb^3＋ concentration even though Gd^3＋ ions were completely replaced by Tb^3＋ ions. The Ce^3＋ ion as a sensitizer could efficiently improve the performance of Tb^3＋ ion. First, with Ce^3＋ co-doping, the excitation spectrum of Tb^3＋ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3＋ monitored at 416 nm. Second, the quantum yields of Sr3Gd2（Si3O9）2：Tb^3＋ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3＋. Finally, the co-doping of Ce^3＋ was also effective to improve the thermal stability of Sr3Gd2（Si3O9）2：Tb^3＋. As the temperature rose to 150 oC, the emission intensity of Tb^3＋ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG：Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2（Si3O9）2：Tb^3＋,Ce^3＋ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.
基金Project supported by National Natural Science Foundation of China (20976002)Beijing Municipal Natural Science Foundation(2122012)+2 种基金Key Projects for Science and Technology of Beijing Education Commission (KZ201310011013)Project of Transformation and Industrialization of College Scientific & Technological AchievementsProjects of the Combination of Manufacture,Education & Research of Guangdong Province (2011B090400100)
文摘The strong yellow upconversion （UC） light emission was observed in Ho3＋/yb3＋ co-doped Gd2M0309 phosphor under the excitation of 980 nm diode laser. The phosphors were synthesized by the traditional solid-state reaction method. The structures of the samples were characterized by X-ray diffraction （XRD）. Under 980 nm excitation, Ho3＋/yb3＋ co-doped Gd2Mo3O9 exhibited strong yellow UC emission based on the green emission near 541 nm generated by 5F4,5S2→5i8 transition and the strong red emission around 660 nm generated by 5F5→5I8 transition, which assigned to the intra-4f transitions of Ho3＋ ions. The doping concentrations of Ho3＋ and Yb3＋ were determined to be 0.01 mol Ho3＋ and 0.2 mol Yb3＋ for the strongest yellow emission. Then the dependence of UC emis- sion intensity on excitation power density showed that the green and red UC emissions were involved in two-photon process. The possible UC mechanisms for the strong yellow emission were also investigated. The result indicated that this material was a promis- ing candidate for the application in the yellow display field.
