White-light long-lasting phosphor Sr2MgSi2O7:Dy3+

A Sr2MgSi2O7:Dy3+ phosphor emitting long-lasting white light was prepared and investigated. Under the ultraviolet excitation, the emission spectra of Sr2MgSi2O7:Dy3+ are composed of a broad band peaking at 441 nm from the host and the characteristic emission of Dy3+ peaking at 480, 575 and 668 nm, originating from the transitions of 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 in the 4f9 configuration of Dy3+. After stopping the excitation, the afterglow spectra consist of only emissions from the transitions of Dy3+ and the emission band from the host does not contribute to the afterglow spectra. The red-light emission peaking at 668 nm from the transitions of 4F9/2→6H11/2 is rather weak. Therefore, the afterglow spectra are composed of intense blue-light emission peaking at 480 nm and yellow-light emission peaking at 575 nm, showing white-light for human eyes. The white-light afterglow can last about 40 min in darkness after excitation with 254 nm for 10 min (250 μW/cm2). The afterglow decay curves can be fitted into hyperbolic curve. The thermoluminescence curves show two thermoluminescence bands peaking at about 295 and 330 K, which are responsible for the long-lasting afterglow emission.