Photoluminescence of lanthanide-doped CaSi2O2N2 phosphors and the energy-level diagram of lanthanide ions in CaSi2O2N2

Abstract Lanthanide-doped CaSi 2 O 2 N 2 phosphors were synthesized by solid-state reaction. Their photoluminescence (PL) properties were investigated and analyzed systematically. Energy transitions attributed to electron transfers from 4f to 4f (ff), from 4f to 5d (fd), from 5d to 4f (df) and charge transfer (CT) transition were obtained and classified. Finally, an energy-level diagram of lanthanide-ions in CaSi 2 O 2 N 2 was proposed. The diagram matches perfectly with the experimental results and explains the luminescence properties of lanthanide-doped CaSi 2 O 2 N 2 phosphors. The electron-vibrational interaction in 4f–5d optical transitions of CaSi 2 O 2 N 2 :Eu 2+ was also studied.