VUV-excited luminescence properties of Tb3+ activated BaGdB9O16

The single phase of BaGd1-xTbxB9O16(0.05 <= x <= 0.3) was prepared by the solid-state reaction. Their photoluminescence properties were investigated under vacuum ultraviolet (VUV) excitation. Monitored by 541 nm emission, the excitation spectrum of BaGd0.75Tb0.25B9O16, consisted of one broad band centered at about 148 nm and some bands in 163 to 282 nm. The former was assigned to the overlapped absorptions among borate groups, charge transfer bands (CTBs) of O2--->Ln(3+) (Ln=Tb, Gd) and the f-->d transition of Gd3+. The bands in 163-282 nm were ascribed to the 4f(8)-->4f(7)5d(1) transitions of Tb3+. The maximum emission peak was observed at 541 nm and the optimum emission was obtained x=0.25 in BaGd1-xTbxB9O16(0.05 <= x <= 0.3) under 147 nm excitation. The decay time decreased gradually with the increase of Tb3+ concentration in BaGd1-xTbxB9O16. Compared with commercially available phosphor Zn2SiO4:Mn2+, the optimum phosphor BaGd0.75Tb0.25B9O16 exhibited about 40% integrated emission intensity under 147 nm excitation, with chromaticity coordinates of (0.34, 0.55) and the shorter decay time of about 3.17 ms.