White-light long-lasting phosphorescence from Tb3+-activated Y2O2S phosphor

The white-light long-lasting phosphors Y2O2S:Tb3+, Sr2+ or/and Zr4+ were prepared and studied. The white-light afterglow emission after the irradiation with 254 nm UV are composed of the blue light emission and the yellowish-green light emission, originating from the transitions of 5D3→7F5, 5D4→7F5 in Tb3+ when the Tb3+ concentration is not higher than 0.3 at%. The codoped Sr2+ and Zr4+ ions act as trap-creating ions. The afterglow can last over 21 min in the dark for Y2O2S:Tb3+0.3%, Sr2+4%, Zr4+4% after irradiation by 254 nm ultraviolet light. Y2O2S:Tb3+ may be a promising material for the development of white-light long-lasting phosphor since the Tb3+ has a high luminescent efficiency and the dominant excitation band of 4f →5d is located at 220–300 nm.