Optical properties of (Y,Tb)PO4 under VUV excitation

(Y,Tb)PO4 were prepared by solid state reaction and their photoluminescence (PL) spectra were investigated under vacuum ultraviolet (VUV) excitation. The obtained results indicate that (Y,Tb)PO4 can efficiently absorb the energy in the region of 112–243 nm and transfer it to the 5D4 energy level of Tb3+. After that, green light is emitted by Tb3+ due to the transitions from 5D4 energy level to the ground state. Under 147 nm excitation, the optimal emissive intensity is obtained when Tb3+ concentration is about 20%, which is about 110% of commercial phosphor Zn1.96SiO4:0.04Mn2+ with chromaticity coordinates of (0.354, 0.553) and the decay time of about 2.527 ms. According to the obtained experimental data, we tentatively explain the energy absorption, transfer and luminescent quenching for YPO4:Tb3+ under 147 nm excitation.