Luminescent properties of Tb3+ activated GdTaO4 with M and M′ type structure under UV-VUV excitation

The photoluminescence of Tb3+ doped M and M′ type gadolinium orthotantalate Gd1−xTbxTaO4 (0.01≤x≤0.20) was investigated under ultraviolet and vacuum ultraviolet excitation. For the samples of Gd1−xTbxTaO4 with different crystallographic structures, emission spectra were the same in addition to intensity; the optimal concentration for Tb3+ was about 10 mol % in M type Gd1−xTbxTaO4 but 5 mol % in M′ type Gd1−xTbxTaO4. These differences could be corresponding with the difference in structures. In addition, compared to commercial Zn2SiO4: Mn2+, the integrated intensity of M and M′ type GdTaO4: Tb3+ could reach 67% and 85%, respectively, of that at 147 nm excitation, which indicates that GdTaO4: Tb3+ would be a promising vacuum ultraviolet phosphor for application in PDP and Hg-free lamp.