Energy Transfer from Ce3+ to Tb3+ /Dy3+ /Mn2+ in Ca9 Ga(PO4 )7 Phosphors: Synthesis, Structure and Tunable Multicolor Luminescent Properties.

ABSTRACT

A series of Ca9 Ga(PO4 )7Ce3+ /Tb3+ /Dy3+ /Mn2+ phosphors with tunable color, in which Ce3+ acts as the sensitizer, was synthesized. Energy transfer (ET) from Ce3+ to Tb3+ /Dy3+ /Mn2+ was investigated in detail. Tb3+ /Dy3+ /Mn2+ single-doped Ca9 Ga(PO4 )7 can exhibit green, yellow, and red emission, respectively. Incorporating Ce3+ into a Tb3+ /Dy3+ /Mn2+ single-doped Ca9 Ga(PO4 )7 phosphor can remarkably promote the luminous efficiency of the Tb3+ /Dy3+ /Mn2+ ions. This enhancement originates from an efficient ET from Ce3+ to Tb3+ /Dy3+ /Mn2+ . The ET was validated by luminescence spectra, decay dynamics, and schematic energy levels. Moreover, the intensity ratio of red emission of Mn2+ to violet emission of Ce3+ was analyzed based on energy-transfer and lifetime measurements. In Ce3+ -Tb3+ , Ce3+ -Dy3+ , and Ce3+ -Mn2+ doped Ca9 Ga(PO4 )7 , the emitting color changed from violet to green, yellow, and red, respectively, which indicates the potential use of this new tunable phosphor in UV light-emitting diodes.