Yb3+,Tm3+co-doped Gd6 Mo O12phosphors with different morphologies are prepared by the hydrothermal method.The dendrites present different morphologies(including hexagonal prisms,spindles,and spheres) after changing the p H value and edetate disodium(EDTA) usage.It is found that each of the two factors plays a crucial role in forming different morphologies.The up-conversion(UC) luminescence is studied.Under 980-nm semiconductor laser excitation,relatively strong blue emission and weak red emission are observed.Finally,the effect of pumping power on the UC luminescence properties and the level diagram mechanism of Gd6 Mo O12:Yb3+/Tm3+phosphor are also discussed.
Novel Sr3Gd(1–x)DyxNa(PO4)3F(SGNP:x Dy3+, x=0.01, 0.03, 0.05, 0.07, 0.09, 0.11) phosphors were synthesized by a conventional solid-state reaction method at different compositions. The X-ray diffraction results confirmed that the as-prepared samples were pure phase. The phosphor had two intense emission bands centering at 481 and 574 nm which could be attributed to the 4F9/2→6H15/2 transition and the 4F9/2→6H13/2 transition, respectively. The chromaticity coordinates(x, y) of this phosphor were calculated to be(0.3054, 0.3354) located on the region of white light region when excited at 350 nm. The concentration quenching mechanism of Dy3+ was ascribed to the dipole-dipole interaction. The current research suggested that the phosphors might be potential application in the w-LEDs.
A novel near-infrared (NIR) downconversion (DC) phosphor KSrPO4 :Eu2+ , Pr3+ is synthesized by the conventional high temperature solid-state reaction. The Eu2+ acts as an efficient sensitizer for Pr3+ in the KSrPO4 host. With broad-band near-ultraviolet light excitation induced by the 4f→5d transition of Eu2+ , the characteristic NIR emission of Pr3+ , peaking at 974 nm and 1019 nm due to 3P0 → 1G4 and 1G4 → 3H4 transitions, is generated as a result of the energy transfer from Eu2+ to Pr3+ . The luminescence spectra in both the visible and the NIR regions and the decay lifetime curves of Eu2+ prove the energy transfer from Eu2+ to Pr3+ . This Eu2+ and Pr3+ co-doped KSrPO4 phosphor may be a promising candidate to modify the spectral mismatch behavior of crystalline solar cells and sunlight.
Ba_3Lu(PO_4)_3:Dy^(3+) phosphors were successfully synthesized by conventional solid state reaction and its photoluminescence properties were investigated by X-ray diffraction(XRD),photoluminescence spectra and diffuse reflectance spectra,respectively.Results showed that the phosphor could be excited by the ultraviolet visible light in the region from 320 to 460 nm,and it showed two dominant emission bands peaking at 484 nm(blue light) and 575 nm(yellow light) which originated from the transitions of^4F_(9/2)→~6H_(15/2) and ~4F_(9/2)→~6H_(13/2) of Dy^(3+),respectively.According to Dexter's theory,the concentration quenching mechanism occurred via the electric dipole-dipole interaction.The lifetime values of Dy^(3+) ions at different concentrations(x=0.01,0.03,0.05,0.08 and0.10) were determined to be about 0.8556,0.7595,0.6864,0.6059 and 0.5456 ms.
