The properties of a novel green long afterglow phosphor Zn2GeO4:Mn2+, Pr3+

• The Zn2GeO4:Mn2+, Pr3+ phosphor possess a persistent luminescence property.
• The green long afterglow of Zn2GeO4:Mn2+, Pr3+ can last for three hours.
• The Zn2GeO4 may be an excellent host material for Mn2+-based long afterglow.
• Pr3+ ions served as trap center, which can greatly postpone the afterglow.

Novel Zn2GeO4:Mn2+, Pr3+ long afterglow phosphor was successfully synthesized by the high temperature solid state reaction. Long afterglow properties of the sample has been investigated in detail by measuring the X-ray diffraction (XRD), excitation spectrum, emission spectrum, afterglow spectrum, decay curve and thermoluminescence curve. The X-ray diffraction phases indicate that the co-doped Mn2+, Pr3+ have little influence on the crystal structure of Zn2GeO4. According to the emission spectra, we found that the Zn2GeO4:Mn2+, Pr3+ exhibit a narrow band emission with the peak at 532 nm, which could be ascribed to Mn2+ transition between 4T1 and 6A1 electron configurations. The green long afterglow of Zn2GeO4:Mn2+, Pr3+ could be observed for three hours by naked eyes at room temperature under 254 nm UV excitation. The thermoluminescence (TL) curve is employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence. The results suggest that Zn2GeO4 may be an excellent host material for Mn2+-based long afterglow. Furthermore, the function of co-doped Pr3+ ions is confirmed as trap center, which can greatly postpone the afterglow emission properties of Mn2+.