Luminescence Properties of Sr₂SnO₄:Sm³⁺ Afterglow Phosphor

A new long-lasting phosphorescence (LLP) phosphor, Sr₂SnO₄:Sm³⁺ which emits reddish-orange LLP upon UV-excitation, is prepared by a conventional high-temperature solid-state method. After irradiation under 247-nm UV light, Sr₂SnO₄:Sm³⁺ emits an intense reddish-orange emission afterglow from the ⁴G_5/2 to ⁶H_J (J = 5/2,7/2,9/2) transitions. The afterglow decay curve of the Sm³⁺-doped Sr₂SnO₄ phosphor contains a fast decay component and another slow decay one. Due to the presence of the slow decay component, the afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source.