Luminescence and Trapping in Phosphors Containing Gallium

A study was made of the effects of gallium impurity on the luminescence emission and trapping in phosphors with oxygen-dominated host crystals and in phosphors with zinc sulfide host crystal. Gallium acts (1) as an intensifier for host-crystal emissions in zinc silicate, magnesium silicate, and zinc sulfide phosphors; (2) as an originative activator in zinc germanate phosphor; (3) as a poison for emissions resulting from manganese activator in silicate and germanate phosphors, and for emissions caused by copper and manganese in zinc sulfide phosphors for cathode-ray excitation; (4) as a sensitizer for emissions resulting from copper and manganese in zinc sulfide phosphors for ultraviolet excitation; (5) as a trapping agent in zinc silicate, magnesium silicate, zinc germanate, and zinc sulfide; (6) as a trapping poison in beryllium silicate phosphors. Evidence is found for a correlation between types of emission centers and trapping centers in silicate and germanate phosphors. Results on intensification indicate that intensifier activators are effective in increasing the intensity of host-crystal emissions by introducing crystal defects of the same type as those formed by random thermal processes in the preparation of the phosphor.