Search

A series of KY(VO):Eu phosphors were synthesized by a high-temperature solid-state reaction method. The luminescence properties were characterized by means of photoluminescence excitation and emission spectra, CIE chromaticity, and concentration quenching. The excitation spectrum exhibits a broad band centered at about 324 nm in the region from 215 to 375 nm corresponding to an overlap of the charge transfer transitions of VO and O → Eu. The present phosphors exhibit green and red colors due to the host emissions of host and Eu ions. The intensity ratio of D → F to D → F is highly dependent on the Eu ions concentration due to the structure change of host. Eu-doped KY(VO) phosphors show tunable CIE color coordinates from green to red dependent on Eu content and excitation wavelength. The ideal red and warm white lights have been obtained from the phosphors by appropriately adjusted excitation wavelength. The results indicate that KY(VO):Eu is potential phosphors for white light-emitting diodes applications and color display devices. [ABSTRACT FROM AUTHOR]

Sr 3− x Eu x MoO 6 and Sr 2.7 Eu 0.3 Mo 1− y W y O 6 red phosphors were successfully synthesized by solid-state reaction method at 1260 °C for 6 h. The photoluminescence (PL) properties of Eu 3+ in this phosphor material were investigated by analyzing the excitation and emission spectra and the effect of Eu 3+ concentration. X-ray diffraction (XRD) patterns indicate the formation of Sr 3 MoO 6 :Eu 3+ pure phase. The excitation and emission spectra demonstrate that 30 mol% Eu 3+ :Sr 3 MoO 6 shows a broad charge-transfer (CT) band at around 365 nm and an intense red emission (616 nm, 5 D 0 → 7 F 2 transition), with Commission Internationale de I׳Eclairage (CIE) chromaticity coordinates (0.619, 0.376). The substitution of Mo 6+ with W 6+ results in a considerable enhancement of luminescence intensity and improved red color purity. All the results imply that the studied phosphors may be a promising red component for the application in the white light emitting diodes. [ABSTRACT FROM AUTHOR]

A series of Dy 3+ or/and Eu 3+ doped Y 2 Mo 4 O 15 phosphors were successfully synthesized at a low temperature of 600 °C via solid state reaction. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electronic microscope (SEM), photoluminescence (PL) excitation, emission spectra and PL decay curves. XRD results demonstrate that Y 2 Mo 4 O 15 : Dy 3+ , Eu 3+ has the monoclinic structure with the space group of p21/C(14). Under the excitation of ultraviolet (UV) or near-UV light, the Dy 3+ and Eu 3+ ions activated Y 2 Mo 4 O 15 phosphors exhibit their characteristic emissions in the blue, yellow and red regions. The emitting light color of the Y 2 Mo 4 O 15 : 0.08Dy 3+ , y Eu 3+ phosphors can be adjusted by varying the concentration ratio of Dy 3+ to Eu 3+ ions and a white light is achieved when the doping concentration of Eu 3+ is 5%. In addition, the energy transfer from Dy 3+ to Eu 3+ is also confirmed based on the luminescence spectra and decay curves. [ABSTRACT FROM AUTHOR]

Novel Eu 3+ activated Gd 2 Mo 4 O 15 phosphors were synthesized at the comparatively low temperature of 700 °C via solid-state reaction. X-ray powder diffraction results demonstrate that the phosphors crystallize in the triclinic crystal structure, the space group P I ¯ . The photoluminescence spectra and ultraviolet-visible (UV–vis) reflectance and transmittance spectra indicate that Eu 3+ doped Gd 2 Mo 4 O 15 phosphors show a broad and strong absorption band covering ultraviolet (UV) and near ultraviolet (NUV) regions and the crystals emit red light with peak maximum at about 618 nm under excitation of UV, NUV or blue light. The optimal doping concentration of Eu 3+ ions in Gd 2 Mo 4 O 15 phosphors is around 50 mol% and the main concentration quenching mechanism is determined to be the exchange interaction. [ABSTRACT FROM AUTHOR]