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

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.