Blue and red long lasting phosphorescence (LLP) in β-Zn 3(PO 4) 2:Mn 2+,Zr 4+

Abstract

Multi-color long lasting phosphorescent (LLP) phenomenon in β-Zn 3(PO 4) 2:Mn 2+,Zr 4+ was systematically investigated. It is found that the red ( λ Em=616 nm) LLP performance of Mn 2+ such as brightness and duration is largely improved, and that the blue ( λ Em=475 nm) LLP of Zr 4+ with lower intensity appears when Zr 4+ ions are co-doped into the matrix. The fluorescence, phosphorescence and thermoluminescence (TL) spectra show that Mn 2+ ion is solely expected as a luminescent center, while Zr 4+ ion not only acts as a luminescent center, but also induces an electron trap (Trap Zr) associated with a TL peak at 344 K. The trap depth for Trap Zr is 0.25 eV, while that for the intrinsic trap is 0.38 eV, associated with a dominant peak at 385 K for Zn 3(PO 4) 2:Mn 2+. The Zr 4+-induced trap with suitable depth is responsible for the improvement of the red LLP of Mn 2+ ion and the appearance of the blue LLP of Zr 4+ ion. The LLP mechanism is also investigated.