The effect of binder on the d-c characteristics of eleotroluminescent ZnS: Mn, Cu, Cl phosphor powder dispersed in a plastic (polymethylmethacrylate) binder was investigated. A plot of the current-voltage characteristic showed that I = Io exp A/V/VI, where Io and VI are constants for a given sample, suggesting current limited by Schottky emission from Cu-rich lines in the phosphor. As the phosphor concentration in the binder is increased, V[ decreases to a nearly constant value much smaller than calculated for a uniform electric field in an insulator. This result indicates that Schottky emission occurs at points of field concentration, such as at the ends of Cu-rich lines.

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