Long afterglow properties of Eu2+/Mn2+ doped Zn2GeO4

Zn2GeO4:Eu2+0.01 and Zn2GeO4:Mn2+0.01 long afterglow phosphors were synthesized via a high temperature solid state reaction. X-ray diffraction (XRD), afterglow spectra, decay curves and thermoluminescence curves were utilized to characterize the samples. The X-ray diffraction phases indicate that the doping of small amount of transition metal ions or rare earth ions has no significant influence on the crystal structure of Zn2GeO4. According to the afterglow spectra, we found that the Zn2GeO4:Eu2+0.01 exhibits a broad band emission with a peak at 474 nm, which could be ascribed to Eu2+ transition between 4f65d1 and 4f7 electron configurations. The Zn2GeO4:Mn2+0.01 shows a narrow band emission peaking at 532 nm corresponding to the characteristic transition of Mn2+(4T1→6A1). The thermoluminescence (TL) curves above room temperature are employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence. The results indicate that Zn2GeO4 may be an excellent host material for the rare earth ions or transition metal ions long afterglows.