Some Properties of Zinc Sulfide Activated with Copper and Cobalt

Abstract

Some properties of ZnS-Cu-Co phosphors under 3650 .~ excitation are described, viz., the thermal glow, decay, and buildup of fluorescence, temperature dependence, and light sum. Most of the experimental results can be explained by a model in which cobalt levels act both as electron traps with a trap depth of 0.5 electron volt (ev), and as ~c-ceptors for holes, ejected thermally from copper centers with an activation energy of 1.1 ev. The possibility of excitation by 3650 A radiation of electrons from traps to the conduction band is introduced to explain the observed intensity dependence of the light suln.

Structural and optical properties of SrS nanophosphors influenced by Ce 3+ ions concentrations and particle size reduction

“…Till the end of last century, modest research was carried out on the phenomenon of long lasting phosphorescence (LLP). Before that, for several decades copper doped zinc sulfide (ZnS: Cu) and later copper and cobalt doped zinc sulfide (ZnS: Cu, Co) have been the most eminent and extensively used luminescent phosphors [7,8]. They were applied in numerous commercial appliances including glowing watch dials, luminous paints, toys that glow in the dark and many more.…”

Luminescence in KI:Tl

“…The slow build-up of luminescence has been observed by Randall and Wilkins (1945), by Levialdi and Luzatti (1947), by Hoogenstraten (1953), and by Hoogenstraten and Klasens (1953) for luminophors which showed also a slow phosphorescent decay. Except for the present case of KI:TI, slow build-up together with very fast decay has only been observed for mixed AgI-AgBr by Moser and Urbach (1957 …”

Developments in Luminescence and Display Materials Over the Last 100 Years as Reflected in Electrochemical Society Publications

“…Klasens 30 discussed the nature of fluorescent centers and traps in ZnS with S 2Ϫ impurity. Hoogenstraaten and Klasens 31 presented the luminescence of ZnS:Cu,Co phosphors and described the role of ''killer'' centers, namely, additional impurities responsible for the drop of the fluorescence efficiency. In a series of three papers, Ewles and Lee 32 discussed the role of large activation centers in crystal phosphors, and reported the luminescence properties of CaO crystals with different impurities.…”