Luminescence properties and energy transfer in Tb3+ and Eu3+ co-doped Ba2P2O7 phosphors

Abstract

The Ba₂P₂O₇:Tb³⁺, Eu³⁺ phosphors were synthesized by a high temperature solid-state reaction method in air atmosphere and their crystal structures, lifetime, luminescence properties, and energy transfer mechanism were investigated in detail. A series of characteristic emissions of Ba₂P₂O₇:Tb³⁺, Eu³⁺ phosphors were observed in the emission spectra at around 545 nm, 593 nm, and 613 nm when excited at 378 nm. The energy-transfer mechanism from Tb³⁺ to Eu³⁺ in Ba₂P₂O₇ is determined by a dipole–dipole interaction. The emission intensity of Ba_2−xP₂O₇:xEu³⁺ was enhanced by doping charge compensation Li⁺, Na⁺ and K⁺. The CIE coordinates of the phosphors can be tuned from blue-green through white, to yellow and finally to orange-red with changing the Eu³⁺/Tb³⁺ ratio. The average decay time of Eu³⁺ increases from 2.10 to 5.81 ms with the concentration of Tb³⁺ increasing from 2% to 8%, and reaches the maximum at 0.08, and is shortened when the concentration of Tb³⁺ goes beyond 8%.