Fluorescence of Pure Zinc Sulfide in Correlation with Deviation from Stoichiometry

Abstract

Studies were carried out on the correlation between the B and SAL emission bands of pure ZnS phosphors and the deviation from the stoichiometry in the phosphors. SAL is observed in the phosphors having excess zinc, while it disappears in the phosphors having excess sulfur. The SAL center may be caused by a sulfur vacancy. B grows in either case that the phosphors are fired in the atomosphere of zinc or sulfur. The peak of B of the phosphors having excess sulfur is located at 347 mμ, while that of the phosphors having excess zinc at 357 mμ. These facts suggest that the so-called B band is composed of two bands of B_I and B_II. It may be reasonably concluded that the center of B_I is formed by an interstitial sulfur atom and that the center of B_II is caused by an interstitial zinc atom or a sulfur vacancy having the value of charge different from that of the center of SAL.