Luminescence Dependence upon Concentration and Temperature in YPO₄: Pr³⁺

Under selective excitation ³P₀ state of Pr³⁺ ion in YPO₄, the emission spectra and fluorescence decay curves are measured at different concentrations and temperatures. The origin of the spectral line located at 613.2 nm has been discussed and assigned to be the ¹D₂ (Γ₃)→³H₄ (Γ₅) transition. The different concentration dependence of emission intensities of levels ³P₀ and ¹D₂ has been studied. Using static model, the fluorescence decay curve of ¹D₂ level is fitted, and the result shows that the cross-relaxation caused by the interaction of dipole-quadrupole between adjacent Pr³⁺ ions reults in the concentration quenching.