Blue and red long lasting phosphorescence (LLP) in β-Zn3(PO4)2:Mn2+,Zr4+ Original Research Article

Multi-color long lasting phosphorescent (LLP) phenomenon in β-Zn3(PO4)2:Mn2+,Zr4+ was systematically investigated. It is found that the red (λEm=616 nm) LLP performance of Mn2+ such as brightness and duration is largely improved, and that the blue (λEm=475 nm) LLP of Zr4+ with lower intensity appears when Zr4+ ions are co-doped into the matrix. The fluorescence, phosphorescence and thermoluminescence (TL) spectra show that Mn2+ ion is solely expected as a luminescent center, while Zr4+ ion not only acts as a luminescent center, but also induces an electron trap (TrapZr) associated with a TL peak at 344 K. The trap depth for TrapZr is 0.25 eV, while that for the intrinsic trap is 0.38 eV, associated with a dominant peak at 385 K for Zn3(PO4)2:Mn2+. The Zr4+-induced trap with suitable depth is responsible for the improvement of the red LLP of Mn2+ ion and the appearance of the blue LLP of Zr4+ ion. The LLP mechanism is also investigated.