An Orange-Emitting, Long-Persistent Phosphor, Ca[sub 2]Si[sub 5]N[sub 8]:Eu[sup 2+],Tm[sup 3+]

An orange-emitting, long-persistent phosphor, , was developed. Afterglow of this phosphor decays more slowly than that of the conventional red-emitting, long-persistent phosphor, . After 420 nm excitation, the afterglow luminance is initially lower, but, after 8 min, gets higher than luminance of . Long afterglow results from electron traps formed by at the site. The origin of two main thermoluminescence glow peaks at 220 and 350 K is discussed based on their dependence on Eu or Tm concentration and Ca/Si atomic ratio. Increased thermoluminescence intensity is observed by excitation in 4f-5d transition at room temperature followed by the fundamental absorption of the host at low temperature.