Luminescent Properties of Al2O3:Tb3+ Powders Embedded in Polyethylene Terephthalate Films

Abstract

The luminescent properties of Al2O3:Tb3+ powders embedded in polyethylene therephtalate (PET) films have been studied. Luminescent Al2O3:Tb3+ polycrystalline powders were synthesized by a simple evaporation method. X-ray diffraction (XRD) spectrum of powders of Al2O3:Tb3+ have the α-Al2O3 crystalline phase with peaks located at 2Θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, which are associated with the planes (012), (104), (110), (113), (202), (024), (116), (018), (214), (300), (119) and (220), and the δ-Al2O3 phase is also present as identified by peaks in 2Θ = 32.82, 45.8, 61.36 and 66.74, associated with the planes (220), (400), (511) and (440). The powder embedded films were obtained by the spray pyrolysis technique. The photoluminescence and cathodoluminescence emission spectra from these samples show, in both cases, luminescence peaks associated with transitions within the electronic energy levels of Tb3+ ions. The dominant peak is at 544nm corresponding to the 5D4→7F5 transition and present 5D4→7F6, 5D4→7F4 y 5D4→7F3 transitions in 494, 587 y 622nm, when excited with λexc = 299 nm at room temperature. The CIE coordinates for non-doped PET films are (x = 0.2045, y = 0.3636), when excited with 270nm, this emission falls in the blue region. CIE diagram for powder embedded PET films excited with 299 nm have coordinates (x = 0.31, y = 0.5111); in this case, the emission is a combination of Al2O3:Tb3+ green light and PET blue light emissions. UV-Vis % transmission measurements on these films show that they are transparent (~ 80 and 95 %T).