The Host Crystal Luminescence of Zinc Sulfide Phosphors

Abstract

Effects produced on the host crystal luminescence of zinc sulfide phosphors by increasing the preparation temperature without any additives in the preparation, are compared with effects produced by adding halide in the preparation at a fixed temperature. Both methods of altering the luminescence properties of the phosphors produce qualitatively the same results on (1) intensification of the host crystal emission for excitation by 3650A ultraviolet and by 6 kv cathode rays, and for phosphors of both cubic and hexagonal crystal structure, (2) glow curves after excitation by 3650A ultraviolet, (3) diffuse reflectivity for light in the wavelength range from 3400 to 4200A, and (4) the variation of the emission intensity during excitation as a function of operating temperature. Data on the variations, with preparation procedure, of the emission intensity during excitation and of the glow intensity during thermostimulation show that a possible correlation exists between shallow traps and isolated omission defects, and between deep traps and pairs of omission defects; and that a correlation is suggested between luminescence centers and particular perturbed (SZn₄) groups in the crystal. At least a part of the intensification caused by adding halide in the preparation must be attributed to a classical ``flux'' action.