Luminescence properties of a novel orange emission long persistent phosphor CaO:Sm3+

A novel Sm3+-doped CaO phosphor was synthesized by a traditional high temperature solid-state reaction method. The luminescence properties were studied and orange long afterglow was observed for the first time. The dependence of photoluminescence (PL) and long afterglow (LAG) properties on Sm3+ contents were investigated systematically. The optimal concentrations of Sm3+ ions for the best PL and LAG properties were experimentally to be 0.4 and 0.3 mol%, respectively. After irradiation by 254 nm for 3 min, the duration of orange afterglow can last nearly 40 min. The traps caused by the incorporation of Sm3+ ions are responsible for the generation of orange LAG. The mechanism of LAG was also illustrated briefly.