The persistent energy transfer of Eu2+ and Dy3+ and luminescence properties of a new cyan afterglow phosphor α-Ca3(PO4)2:Eu2+,Dy3+

Abstract

A new cyan long-lasting phosphorescence (LLP) phosphor Ca₃(PO₄)₂:Eu²⁺,Dy³⁺ was synthesized by a solid state reaction and its LLP properties were investigated for the first time. The Ca₃(PO₄)₂:Eu²⁺,Dy³⁺ phosphor exhibits two emission bands centered at 480 nm and 573 nm, which are ascribed to the 4f⁶5d¹–4f⁷ electronic transition of Eu²⁺ ions and the transition from ⁴F_9/2 to ⁶H_13/2 of Dy³⁺ ions, respectively. After removal of the excitation source, the bright cyan LLP could be observed for 5 h by the naked eye. Besides, the yellow LLP component originated from the persistent energy transfer (PET) from Eu²⁺ ions to Dy³⁺ ions. The incorporation of Dy³⁺ ions creates more appropriate energy traps and evidently enhances the LLP behavior of Ca₃(PO₄)₂:Eu²⁺ phosphor. A schematic model is constructed to convey trapping/detrapping processes and PET in the material.