Luminescence properties of a novel bluish green long-lasting phosphor LiBaPO4: Eu2+, Ho3+

A novel bluish green long-lasting phosphor LiBaPO4:Eu2+, Ho3+ was synthesized by solid- state reaction. The phosphor was characterized by X-ray diffraction, photoluminescence spectra, afterglow decay curve and thermoluminescence spectrum. The photoluminescence is ascribed to the 5d-4f transitions of Eu2+ ions. There is no Ho3+ emission in the photoluminescence spectra, which means that Ho3+ is a coactivator. After irradiated with a UV light (365 nm), persistent luminescence can last more than 5626 s above 0.32 mcd/m(2), which is 100 times than the sensitivity of human eyes in dark. Thermoluminescence curves indicate that only one trap depth in the phosphor, which is ascribed to the doping of Ho3+. The possible mechanism of persistent luminescence was discussed.