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

Highlights: • A red long persistent phosphor of β-Zn₃(PO₄)₂: Mn²⁺, Dy³⁺ was synthesized. • Dy³⁺ as a sensitizer transfers its energy to the luminescent center of Mn²⁺. • The three factors are responsible for the improvement of LPP properties. - 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 620 nm, which can be assigned to the ⁴T_1g → ⁶A_1g 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 4 h in the limit of light perception for naked eyes when excited under 254 nm UV light for 5 min. 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