Phosphorescence behavior and photoluminescence mechanism of Dy3+ sensitized β-Zn3(PO4)2: Mn2+ phosphor

Abstract

A red long persistent phosphor (LPP) of β-Zn3(PO4)2: Mn2+, Dy3+ was synthesized conventionally via homogeneous coprecipitation and conventional solid-state sintering methods. The emission peak of phosphor was found at 620nm, which can be assigned to the 4T1g→6A1g transition of Mn2+. The decay curves of phosphors show that Dy3+ ions co-doping can largely improve the performance of the red LLP of β-Zn3(PO4)2: Mn2+. This red long-persistent luminescence was observed for about 4h in the limit of light perception for naked eyes when excited under 254nm UV light for 5min. Thermoluminescence analysis indicates that the dopant of Dy3+ ions produced suitable trap depth of defects that enhanced the luminescence of LPP. It is hypothesized that Dy3+ as a sensitizer transfers its energy to the luminescent center of Mn2+. We propose that the emission mechanism of LPP experiences a series process of electron–hole pairs: production, release, movement and combination. The decay time of LPP has close relationship with the life span of electron–hole pairs during their releasing time from traps and moving length on their path.