Investigation of new color-tunable up-conversion phosphors and their long-persistent luminescence properties for potential biomedical applications

Long-persistent phosphor and up-conversion particles used for optical imaging continue to interest researchers. The present work identifies an Er 3+ doped micro-sized CSAO-CSO mixed material that exhibits both up-conversion and persistent luminescence. The cross-relaxation that occurs among Er 3+ ions contributes to enhancing the up-conversion intensity. The Tm 3+ /Ho 3+ co-doped strategy was used to induce tunable up-conversion colors. The cross-relaxation process corresponding to the energy transfer mechanism was investigated via the luminescence lifetimes of Er 3+ . Moreover, the persistent luminescence and thermo-luminescence properties of CSAO-CSO: Er 3+ were also investigated systematically. Our results combine the fields of up-conversion and persistent luminescence, which may support other explorations of new kinds of long-persistent and up-conversion materials.