Novel emission-tunable oxyapatites-type phosphors: Synthesis, luminescent properties and the applications in white light emitting diodes with higher color rendering index.

Developing color-tunable phosphors via the introduction of co-doping activators and sensitizers to the host with energy transfer processes has been a state-of-the-art topic for a long time. In this work, novel emission-tunable oxyapatites-type Ba 10 (PO 4 ) 6 O:Eu 2+ ,Tb 3+ /Li + phosphors were prepared via a high temperature solid state reaction for the applications in white light emitting diodes ( w -LEDs) with higher color rendering index. Tunable colors from blue to green can be realized in the Ba 10 (PO 4 ) 6 O:Eu 2+ ,Tb 3+ /Li + by varying the relative ratios of Eu 2+ to Tb 3+ , showing good absorption in the range of 230–400 nm. The energy transfer mechanism from Eu 2+ to Tb 3+ ions was demonstrated to be a quadrupole-quadrupole interaction by combining the Inokuti-Hirayama (I H) model and Reisfeld's approximation. Importantly, a prototype white lamp was packaged by mixing Ba 9.83 (PO 4 ) 6 O: 0.03Eu 2+ , 0.07Tb 3+ , 0.07Li + and commercial red phosphor CaAlSiN 3 : Eu 2+ , and the lamp exhibits a higher color rendering index (Ra = 92 and R9 = 56) and warm correlated color temperature of 4361 K for the actual application. Better luminescent properties compared to commercial Y 3 A l5 O 12 :Ce 3+ -based w -LEDs, indicating that Ba 10 (PO 4 ) 6 O: Eu 2+ , Tb 3+ /Li + phosphors are emerging as potential phosphor-converted w -LEDs. [ABSTRACT FROM AUTHOR]