Cathodoluminescent Properties of ZnS:Ce, Li Phosphor

The bluish-green cathodoluminescence of ZnS:Ce, Li has been investigated while varying the firing temperature, Ce and Li concentrations. Bright luminescence of Ce3+ is obtained only when the samples are quenched from a temperature higher than 1000°C in a sulfur atmosphere containing Li. The optimum concentration of Ce is 5×10-5–10-4 g. atom/mol. The Li concentration should be higher than that of Ce for efficient luminescence. The maximum energy conversion efficiency of the as-quenched samples is about 12%. The luminescence efficiency is greatly decreased by heat-treatment at temperatures below 900°C, probably because of segregation of Li ions. Noble metals and other Ia elements are not such efficient sensitizers as Li for Ce3+ luminescence.