Generation of orange and green emissions in Ca2GdZr2(AlO4)3:Ce3+, Mn2+, Tb3+ garnets via energy transfer with Mn2+ and Tb3+ as acceptors

Abstract

Utilizing Mn²⁺ and Tb³⁺ ions as energy-transfer acceptors, we report a series of emission color-tunable Ca₂GdZr₂(AlO₄)₃:Ce³⁺, Mn²⁺, Tb³⁺ aluminate garnets. Incorporating Mn²⁺ and Tb³⁺ into Ca₂GdZr₂(AlO₄)₃:Ce³⁺ phosphor generates an orange emission band peaking at 572 nm and a green line peaking at 550 nm. The energy transfers from Ce³⁺ to Mn²⁺ and Ce³⁺ to Tb³⁺ ions are deduced from the spectral overlap between the Ce³⁺ emission and Mn²⁺/Tb³⁺ excitation spectra. Fluorescence decay patterns are studied as a function of Mn²⁺ and Tb³⁺ concentration. The calculated values based on the luminescence dynamical process indicate that the intensity ratios of the orange to green bands as a function of Mn²⁺ concentration are in good agreement with those obtained directly from the emission spectra. We have demonstrated that the color emission as well as the luminescence external quantum yield (20.4–48.9%) can be tuned by precisely controlling the content of Ce³⁺, Mn²⁺, and Tb³⁺. The energy transfer significantly enables the achievement of a broad emission spectrum covering an orange spectral region. It is suitable for near-UV light-emitting diode (LED) excitation.