Long-lasting phosphorescence in Ce3+-doped Ca2Al2SiO7 and CaYAl3O7 crystals

Long-lasting phosphorescence is observed in ${\mathrm{Ce}}^{\mathrm{3+}}$ -doped ${\mathrm{Ca}}_{\mathrm{2}}{\mathrm{Al}}_{\mathrm{2}}{\mathrm{SiO}}_{\mathrm{7}}$ (CASM) and ${\mathrm{CaYAl}}_{\mathrm{3}}{\mathrm{O}}_{\mathrm{7}}$ (CYAM) crystals at room temperature. UV irradiation at 365 nm produces broadband emissions with peaks at 417 nm for CASM and 425 nm for CYAM, which persist for not less than 1 h after the removal of the irradiating light. Based on the time dependence of the intensity of the phosphorescence, the long-lasting phosphorescence in these crystals is considered to be due to the electron–hole recombination at shallow traps, which occurs by a thermally activated process.