Luminescence properties of LaPO4:Tb,Me (Me = Gd, Bi, Ce) under VUV excitation

The luminescence properties of LaPO₄:Tb³⁺,Me³⁺ (Me = Gd, Bi, Ce) were investigated under VUV excitation. The results indicate that only Gd³⁺ plays an intermediate role in energy transfer from the host absorption band to Tb³⁺ under 147 nm excitation, Bi³⁺ and Ce³⁺ have no contribution to improving the emission intensity of La_0.95PO₄:Tb_0.05³⁺ because the charge transfer band of Bi³⁺ is mismatching for the excitation wavelength (147 nm) and Ce³⁺ can be oxidized easily. A new band at 135 nm is observed in the excitation spectrum of La_0.92PO₄:Tb_0.05³⁺,Bi_0.03³⁺, which may correlate with the absorption of Bi²⁺.