Calcium tungstate phosphors activated by the Ln3＋ ions （Ln-Pr, Nd, Tb, Yb） were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were charact...Calcium tungstate phosphors activated by the Ln3＋ ions （Ln-Pr, Nd, Tb, Yb） were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by scanning electron microscopy （SEM）, X-ray powders diffraction （XRD） and infrared spectra （FT-1R）. The samples were fotmd to show luminescence properties （down-conversion, DC, at excitation wavelength 254 nm and up-conversion, UC, at excitation wavelength 980 nm）. CaWO4 doped with Tb3＋/yb3＋ showed green DC and UC luminescence characteristic of Tb（Ⅲ） ion in the range of 470-660 nm, cor- responding to the 5D4→7F6,5,4,3,2 electronic transition. CaWO4 doped with Pr3＋/Yb3＋ showed week blue, green and red （DC and UC） luminescence of Pr（Ⅲ） ion, in the wavelength region of 450-700 nm. Emission peaks were ascribed to the 3P1→3H4,5,6, 3P0→3H4,5,6, 3P1→3F2 and 3P0→3F2 transitions, respectively. CaWO4 doped with Nd3＋/yb3＋ phosphor emitted orange UC luminescence at 450-690 nm （2p3/2→4I15/2, 4G7/2→419/2,11/2,13/2） and strong near-infrared UC luminescence at 720-900 nm （4F7/2＋4S3/2→4419/2, 4F5/2＋2H3/2→419/2, 4F3/2→4I9/2） which is the characteristic of Nd（Ⅲ） ion.展开更多
CaWO4 phosphor activated by the Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ ions were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were c...CaWO4 phosphor activated by the Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ ions were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method （XRD）, infrared spectra （FT-IR） and scanning electron microscopy （SEM）. The samples were found to show up-conversion luminescence properties. CaWO4 doped with Tm^3＋/Yb^3＋ showed blue luminescence characteristic of Tm（Ⅲ） ion in the range of 460-485 urn, corresponding to the ^1G4→^3H6 electronic transition. CaWO4 doped with Er^3＋/Yb^3＋ showed strong green luminescence at 510-565 nm （^2H11/2, ^4S3/2→^4I15/2） and weak red luminescence at 640-685 nm （^4F9/2→^4I15/2） of Er（Ⅲ） ion. CaWO4 doped with Ho^3＋/Yb^3＋ phosphor emitted green luminescence at 525-560 nm （5S2, 5F4→518） and red luminescence at 6304i70 um （SFs→518） and at 730-770 nm （^5S2, ^5F4→^5I7）, which is the characteristic of Ho（Ⅲ） ion.展开更多
文摘Calcium tungstate phosphors activated by the Ln3＋ ions （Ln-Pr, Nd, Tb, Yb） were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by scanning electron microscopy （SEM）, X-ray powders diffraction （XRD） and infrared spectra （FT-1R）. The samples were fotmd to show luminescence properties （down-conversion, DC, at excitation wavelength 254 nm and up-conversion, UC, at excitation wavelength 980 nm）. CaWO4 doped with Tb3＋/yb3＋ showed green DC and UC luminescence characteristic of Tb（Ⅲ） ion in the range of 470-660 nm, cor- responding to the 5D4→7F6,5,4,3,2 electronic transition. CaWO4 doped with Pr3＋/Yb3＋ showed week blue, green and red （DC and UC） luminescence of Pr（Ⅲ） ion, in the wavelength region of 450-700 nm. Emission peaks were ascribed to the 3P1→3H4,5,6, 3P0→3H4,5,6, 3P1→3F2 and 3P0→3F2 transitions, respectively. CaWO4 doped with Nd3＋/yb3＋ phosphor emitted orange UC luminescence at 450-690 nm （2p3/2→4I15/2, 4G7/2→419/2,11/2,13/2） and strong near-infrared UC luminescence at 720-900 nm （4F7/2＋4S3/2→4419/2, 4F5/2＋2H3/2→419/2, 4F3/2→4I9/2） which is the characteristic of Nd（Ⅲ） ion.
文摘CaWO4 phosphor activated by the Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ ions were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method （XRD）, infrared spectra （FT-IR） and scanning electron microscopy （SEM）. The samples were found to show up-conversion luminescence properties. CaWO4 doped with Tm^3＋/Yb^3＋ showed blue luminescence characteristic of Tm（Ⅲ） ion in the range of 460-485 urn, corresponding to the ^1G4→^3H6 electronic transition. CaWO4 doped with Er^3＋/Yb^3＋ showed strong green luminescence at 510-565 nm （^2H11/2, ^4S3/2→^4I15/2） and weak red luminescence at 640-685 nm （^4F9/2→^4I15/2） of Er（Ⅲ） ion. CaWO4 doped with Ho^3＋/Yb^3＋ phosphor emitted green luminescence at 525-560 nm （5S2, 5F4→518） and red luminescence at 6304i70 um （SFs→518） and at 730-770 nm （^5S2, ^5F4→^5I7）, which is the characteristic of Ho（Ⅲ） ion.
