Synthesis, luminescence and persistent luminescence of europium-doped strontium aluminates

Rare-earth-doped strontium aluminates find many applications. One particular property is persistent phosphorescence. SrAl 2 O 4 :Eu 2 + , Dy 3 + and Sr 4 Al 14 O 25 : Eu 2 + , Dy 3 + are as of today among the best non-radioactive persistent phosphors with afterglow durations exceeding 10 h. In this chapter, we first present the phase diagram and crystal structures of strontium aluminates, before addressing the doping with rare earth ions in these hosts. After presenting the spectroscopy of Eu 2 + in strontium aluminates, we summarize experimental results concerning defects and co-doping in relation to the persistent emission. Finally, we discuss the current understanding of processes underlying persistent luminescence in these inorganic phosphors.