Luminescent Properties of Gd₃PO₇:Eu in UV/VUV Region

The luminescent properties of Gd₃PO₇:Eu were investigated in UV and VUV regions. This phosphor has so strong emissions around 618.5 nm under UV excitation, especially around 209\,nm, so that it has a better colour saturation than that of Y₂O₃:Eu. It would be a new potential red phosphor for lamp and other applications with UV-excitation source or even for displaying device. In the VUV excitation spectrum of Eu³⁺ emissions, energy absorptions by Gd³⁺, Gd-O and PO^3-₄ were observed, on which it can be inferred that there are three kinds of energy transferring processes to Eu³⁺ ions. The energy absorptions of Gd³⁺, Gd-O and PO^3-₄ are induced by 4f → 4f transitions, band-gap transition of Gd₃PO₇ and intramolecular (2t₂ → 2a, 3t₂) transition, respectively. The energy transfer efficiency of the PO^3-₄ intramolecular transition is lower compared with that of the band-gap transition (Gd-O).