Luminescent Properties of Al 2 O 3 :Tb 3+ Powders Embedded in Polyethylene Terephthalate Films

The luminescent properties of Al 2 O 3 :Tb 3+ powders embedded in polyethylene therephtalate (PET) films have been studied. Luminescent Al 2 O 3 :Tb 3+ polycrystalline powders were synthesized by a simple evaporation method. X-ray diffraction (XRD) spectrum of powders of Al 2 O 3 :Tb 3+ have the α-Al 2 O 3 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-Al 2 O 3 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 Tb 3+ ions. The dominant peak is at 544nm corresponding to the 5 D 4 → 7 F 5 transition and present 5 D 4 → 7 F 6, 5 D 4 → 7 F 4 y 5 D 4 → 7 F 3 transitions in 494, 587 y 622nm, when excited with λ exc = 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 Al 2 O 3 :Tb 3+ green light and PET blue light emissions. UV-Vis % transmission measurements on these films show that they are transparent (~ 80 and 95 %T).