Synthesis of Gd1−xTbxAl3(BO3)4 (0.05⩽x⩽1) and its luminescence properties under VUV excitation

Single phases of Gd1−xTbxAl3(BO3)4 (0.05⩽x⩽1) were prepared by the thermal decomposition of the corresponding nitrates. Monitored at 541 nm, the excitation spectra of Gd1−xTbxAl3(BO3)4 (0.05⩽x<1) consisted of one broad band located in the 120–179 nm range and some other bands from 179 to 290 nm. The former could be assigned to the overlapped absorptions among the f→d transition of Gd3+, the charge transfer bands of Ln3+–O2− (Ln=Tb, Gd) and BO3 groups. The latter was ascribed to the 4f8→4f75d transitions of Tb3+. The maximum emission peak was observed at about 541 nm, and the optimum emission was obtained at x=0.5 under 147 nm excitation. The decay time decreased linearly with the increase of Tb3+ concentration. Compared with the phosphor Zn2SiO4:0.08Mn2+, the optimum phosphor Gd0.5Tb0.5Al3(BO3)4 exhibited about 42% emission intensity with chromaticity coordinates of (0.338, 0.579) and the shorter decay time of about 1.945 ms under 147 nm excitation.