White photoluminescence and energy transfer properties of Dysprosium and Europium singly and codoped Na2ZnP2O7 phosphors

Abstract

A series of Dy3+ single doped and Dy3+/Eu3+ codoped Na2ZnP2O7 phosphor was synthesized by conventional solid-state reaction method. The crystal structure, vibrational modes and luminescence properties were researched. The absorption spectrum was analyzed in term of the Judd–Ofelt theory; the intensity parameters Ω2, Ω4, and Ω6 have been evaluated for Dy3+ doped Na2ZnP2O7 sample. The luminescence spectra are dominated by a strong emission in the 574 nm region corresponding to the 4F9/2 → 6H13/2 transition and the optimal doping concentration of Dy3+ is about 4%mol. The optical properties of Dy3+/Eu3+ codoped Na2ZnP2O7 micro crystals were also investigated in order to study the energy transfer between the two ions. The PL spectra of the as prepared samples recorded under the 349 nm, 365 nm and 393 nm excitations show emission peaks of both Dy3+ and Eu3+. The emission intensity of Dy3+ is decreased with increasing Eu3+concentration, which is due to the energy transfer from Dy3+to Eu3+ in the Na2ZnP2O7 host matrix. Furthermore, the chromaticity color coordinates are tuned from the yellowish-white region for the single Dy3+ doped Na2ZnP2O7 to the reddish region for Dy3+/Eu3+co-doped Na2ZnP2O7 samples. This type of luminescence phosphors has promising applications in the fields of W-LEDs, solid-state lighting and optoelectronic devices.