Syntheses and Luminescent Properties of Alkaline-earth Metal Aluminosilicate Phosphors for White LEDs

Abstract

The aluminosilicate based luminescent materials, a series of CaAl2Si2O8:Eu2+ samples were prepared by using a solid state reaction method. The X-ray diffraction patterns of the samples confirmed their triclinic structure after annealed at 1100 °C. The excitation spectra of CaAl2Si2O8:Eu2+ exhibited to longer wavelength broad band in the range from 220 to 420nm and the broad band shifted with increasing Eu2+ concentration. The emission spectrum of CaAl2Si2O8:Eu2+ consists of a broad band from 390 to 550 nm with a maximum wavelength of about 438 nm, which can be ascribed to the electric-dipole-allowed 4f65d1-8S7/2(4f7) transition of the Eu2+ ions. A series of Eu2+ and Mn2+ co-activated CaAl2Si2O8 samples have been synthesized at 1400 °C. The CaAl2Si2O8:Eu2+, Mn2+ samples had a wide emission band ranging from blue to yellow peaking at 438 nm and 550 nm respectively under the excitation of 352 nm irradiation. The PL spectra of CaAl2Si2O8:Eu2+, Mn2+ sample reveals an effective energy transfer from Eu2+ to Mn2+ in CaAl2Si2O8. By utilizing the principle of energy transfer, we have also demonstrated that with appropriate tuning of activator content CaAl2Si2O8:Eu2+, Mn2+ phosphors exhibit great potential to act as a phosphor for white-light-emitting diodes.