PL Properties of Sr2CeO4 With Eu(3+) and Dy(3+) for Solid State Lighting Prepared by Precipitation Method.

Photoluminescence studies of pure and Dy(3+), Eu(3+) doped Sr2CeO4 compounds are presented by oxalate precipitation method for solid state lighting. The prepared samples also characterized by XRD, SEM (EDS) and FTIR spectroscopy. The pure Sr2CeO4 compound displays a broad band in its emission spectrum when excited with 280 nm wavelength, which peaks centered at 488 nm, which is due to the energy transfer between the molecular orbital of the ligand and charge transfer state of the Ce(4+) ions. Emission spectra of Sr2CeO4 with different concentration of Dy(3+) ions under near UV radiation excitation, shows that intensity of luminescence spectra is found to be affected by Dy(3+) ions, and it increases with adding some percentages of Dy(3+) ions. The maximum doping concentration for quenching is found to be Dy(3+) = 0.2 mol % to Sr(2+)ions. The observed broad spectrum from 400 to 560 nm is mainly due to CT transitions in Sr2CeO4 matrix and some fractional contribution of transitions between (4)F9/2 → (6)H15/2 of Dy(3+) ions. Secondly the effect of Eu(3+) doping at the Sr(2+) site in Sr2CeO4, have been studied. The results obtained by doping Eu(3+) concentrations (0.2 mol% to 1.5 mol%), the observed excitation and emission spectra reveal excellent energy transfer between Ce(4+) and Eu(3+). The phenomena of concentration quenching are explained on the basis of electron phonon coupling and multipolar interaction. This energy transfer generates white light with a color tuning from blue to red, the tuning being dependent on the Eu(3+) concentration. The results establish that the compound Sr2CeO4 with Eu(3+) = 1 mol% is an efficient "single host lattice" for the generation of white lights under near UV-LED and blue LED irradiation. The commission internationale de I'Eclairage (CIE) coordinates were calculated by Spectrophotometric method using the spectral energy distribution of prepared phosphors.

Synthesis and characterization of novel Na15 (SO4 )5 F4 Cl:Ce3+ halosulfate phosphors.

A series of Na15 (SO4 )5 F4 Cl phosphors doped with Ce3+ ions was prepared using the wet chemical method. X-Ray diffraction studies were used to determine their phase formation and purity. Fourier transform infrared spectroscopy effectively identified the chemical bonds present in the molecule. The photoluminescence properties of the as-prepared phosphors were investigated and the Ce3+ ions in these hosts were found to give broadband emission in the UV range. For the thermoluminescence study, phosphors were irradiated with a 5 Gy dose of γ-rays from a 60 Co source. Chen's half-width method was employed to calculate the trapping parameters from the thermoluminescence glow curve. Copyright © 2016 John Wiley & Sons, Ltd.

Luminescence study of Eu(3+) doped Li6 Y(BO3 )3 phosphor for solid-state lighting.

In this study, Li6 Y1-x Eux (BO3 )3 phosphor was successfully synthesized using a modified solid-state diffusion method. The Eu(3+) ion concentration was varied at 0.05, 0.1, 0.2, 0.5 and 1 mol%. The phosphor was characterized for phase purity, morphology, luminescent properties and molecular transmission at room temperature. The XRD pattern suggests a result closely matching the standard JCPDS file (#80-0843). The emission and excitation spectra were followed to discover the luminescence traits. The excitation spectra indicate that the current phosphor can be efficiently excited at 395 nm and at 466 nm (blue light) to give emission at 595 and 614 nm due to the (5) D0 → (7) Fj transition of Eu(3+) ions. Concentration quenching was observed at 0.5 mol% Eu(3+) in the Li6 Y1-x Eux (BO3 )3 host lattice. Strong red emission with CIE chromaticity coordinates of phosphor is x = 0.63 and y = 0.36 achieved with dominant red emission at 614 nm the (5) D0 → (7) F2 electric dipole transition of Eu(3+) ions. The novel Li6 Y1-x Eux (BO3 )3 phosphor may be a suitable red-emitting component for solid-state lighting using double-excited wavelengths, i.e. near-UV at 395 nm and blue light at 466 nm. Copyright © 2015 John Wiley & Sons, Ltd.