Low-temperature VUV photoluminescence and thermoluminescence of UV excited afterglow phosphor Sr3AlxSi1−xO5:Ce3+,Ln3+ (Ln = Er, Nd, Sm, Dy and Tm)
Low-temperature (10 K) photoluminescence excitation and emission spectra of undoped Sr3SiO5 as well as Ce3+ and Eu3+ single doped Sr3SiO5 have been investigated. They show the host exciton band and the O2− to Eu3+ charge transfer band at 5.98 eV (207 nm) and 3.87 eV (320 nm) respectively. Low-temperature thermoluminescence measurements are reported for Ce3+ and lanthanide (Er, Nd, Sm, Dy, Er and Tm) co-doped Sr3AlxSi1−xO5. The results show that Ce3+ is the recombination centre and Nd, Sm, Dy and Tm work as electron traps with trap depths of 0.95 eV, 1.89 eV, 1.02 eV, and 1.19 eV, respectively. Thermoluminescence excitation spectra of Sr2.98Al0.02Si0.98O5:0.01Ce3+,0.01Dy3+ show that the traps can be charged by 260 nm UV excitation.