Luminescence properties and energy transfer processes in LiSrPO4 doped with Pr3+ and co-doped with Na+ and Mg2+

The paper studies the influence of co-doping with alkali metal ions (Na+, Mg2+) on fast interconfigurational 5d-4f luminescence in LiSrPO4 doped with Pr3+. Na+ and Mg2+ ions were introduced in order to provide charge compensation and modify the electronic configuration of the materials. Luminescent properties of the powder samples were investigated using time-resolved pulsed cathodoluminescence and luminescence spectroscopy in the UV-VUV spectral region. The obtained results were compared with those obtained earlier on LiSrPO4:Pr3+ without co-dopants. With introduction of the co-dopants, slight changes in relative luminescence intensity and decay time of Pr3+ ion 4f15d1-4f2 radiative transitions were found. The study revealed a complex interplay be- tween defects of crystalline structure and impurity ions leading to the peculiarities in energy relaxation pro- cesses. Energy transfer leading to the delayed recombination processes is responsible for significant afterglow in Pr3+4f15d1-4f2 emission