Photoluminescence of Zinc Silicate Doped with Al and Ti

Photoluminescence of sintered zinc orthosilicate doped with Al or Ti has been measured in the temperature range between 20 and 650 K, peak emissions being noted at 407 and 400 nm, respectively. The corresponding excitation spectra show peaks at 218 and 236 nm for Zn2SiO4:Al and at 218 and 232 nm for Zn2SiO4:Ti. The 218 nm peak must be assigned to the excitation of the undoped zinc silicate where doping with Al as well as Ti effects an enhancement of this band. The two phosphors have different decay times at room temperature (Zn2SiO4: Al,t ≈ 10 sec; Zn2SiO4:Ti,t ≈ 10 −3 sec). We observed the greatest quantum efficiency for the u.v.-blue emission approximately at activator concentrations of 1 mol percent (m/o) Al or 0.6 m/o Ti. Deviations from the linear dependence of the luminescence intensity on the photoexcitation intensity are observed above 400 K.