A white long-lasting phosphor Y2O2S:Tb3+, Sm3+: an improvement of Y2O2S:Tb3+

As an improvement of reported Y2O2S:Tb3+, a white-light long-lasting phosphor: Y2O2S:Tb3+, Sm3+ was prepared by the solid-state reaction. The photo-luminescence spectra showed that the position and shape of Tb3+ and Sm3+ emissions under UV excitation were similar in this host, which ensured a stable white emission color (daylight standard of IEC) under different excitations. The decay curves of co-doped samples indicated that the decay times of emissions of the two ions were close. The thermo-luminescence measurement suggested that the traps created by the doped Sm3+ ions were helpful to postpone the white afterglow of co-doped samples. Therefore, the function of co-doped Sm3+ ions was confirmed as improving the white emission colors of samples and acting as new trap centers.