Energy transfer and multiple photoluminescence of LuNbO4 co-doped with Eu3+ and Tb3+

Abstract

The energy transfer and multiple photoluminescence of LuNbO4:Eu3+,Tb3+ powders were investigated. The photoluminescence spectra of the powders mainly consisted of green and red emission peaks. The green emission peaks (551 nm) were assigned to the 5D4 → 7F5 transition of Tb3+, and the strong red emission peaks (614 nm) originated from Eu3+ (5D0 → 7F2) via a Tb3+ → Eu3+ energy transfer. Tb3+–Eu3+ co-doping greatly enhanced the red emission under UV excitation that could rarely activate Eu3+ ions. The emission of the powders was tunable from green to red by adjusting the ratio of Eu3+/Tb3+, and thus warm white-light-emitting powders could be obtained. The Tb3+ → Eu3+ energy transfer mechanism was explained using the energy transfer efficiency, the critical distance for the Tb3+ → Eu3+ energy transfer, fluorescence decay curves, and multipolar interactions. The results demonstrate that LuNbO4:Eu3+,Tb3+ powders have a high potential for use in UV-pumped white-light-emitting diodes.