Luminescent Properties Of Some Ortho- And Pentaphosphates Doped With Gd~(3+)-eu~(3+): Potential Phosphors For Vacuum Ultraviolet Excitation

摘要

Within the framework of research for new luminescent materials with high quantum efficiency for mercury free lighting devices as well as for plasma display panels, we have studied the rare earth doped phosphates. We have synthesized GdPO_4:Eu~(3+) by solid state reaction at high temperature, LaPO_4:Eu~(3+), Gd~(3+) by hydrothermal method and LaP_5O_(14):Eu~(3+), Gd~(3+) by the flux method. All our pure single-phase samples have been characterized by X-ray diffraction, Raman and Infrared spectroscopies. The excitation and emission spectra were recorded at room temperature. Vacuum ultraviolet (VUV) diffuse reflection spectra show that the forbidden gap of our matrices is close to 160 nm. Unfortunately, excitation spectra revealed that the onset of the charge transfer band of Eu~(3+) overlaps the ~6G_J level of Gd~(3+), making the quantum cutting process unlikely in these materials.