Effects of oxygen vacancies on luminescent properties of green long-lasting phosphorescent (LLP) material α-Zn3(PO4)2: Mn2+, K+

A green long-lasting phosphorescent (LLP) material α-Zn3(PO4)2: Mn2+, K+ was prepared with a joint method of combustion and conventional solid-state sintering. The samples were characterized by X-ray diffraction (XRD), photoluminescence (PL), and thermoluminescence (TL) techniques. The emission band of Mn2+ as luminescent centre was obtained at around 548 nm (green). The emission of the spectrum was assigned to electronic transitions 4T1g-6A1g of Mn2+ ions. The afterglow emission of α-Zn3(PO4)2: Mn2+, K+ phosphor can be distinctly observed in the dark for more than 2 h. The determination of the thermoluminescence (TL) curves shows that the introduction of K+ ions largely enhances the intensity of peak at 309 K and the oxygen vacancies hold excited electrons. Oxygen vacancies catch and store excited electrons for some time to postpone their jumping back to ground levels, which will effectively extend the decay time of α-Zn3(PO4)2: Mn2+, K+.