Wide range yellow emission Sr_8MgLa(PO_4)_7: Eu~(2+) , Mn~(2+) , Tb~(3+) phosphors for near ultraviolet white LEDs

摘要

A series of single phased phosphors Sr8MgLa(PO4)(7): Eu2+, Mn2+, Tb3+ were synthesized by solid state reaction methods for applications of white light emitting diodes(w-LEDs). The broad absorption band at the near ultraviolet (NUV) region of 250-450 nm was obtained, which is ascribed to the 4f(7) - 4f(6)5d(1) electronic transition of the Eu2+ ions. Under NUV excitation, the broad yellow emission was obtained from tri-activated Sr8MgLa(PO4)(7) phosphors via combining three emission bands centered at 500, 550, and 600 nm contributed by Eu2+, Tb3+ and Mn2+, respectively. The optimized concentrations of Mn2+ and Tb3+ were 6 mol%, respectively, which enhanced the total PL intensity up to 30% comparing to only Eu2+ doped phosphor. Moreover, the quantum efficiency of Sr8MgLa(PO4)(7): Eu2+, Mn2+, Tb3+ phosphor had achieved up to 52%. The combination of a NUV chip with compound of Sr8MgLa(PO4)(7): Eu2+, Mn2+, Tb3+ and BaMgAl10O17:Eu2+ achieved tunable w-LEDs with high CAI. The results suggest that this single phased Sr8MgLa(PO4)(7): Eu2+, Mn2+, Tb3+ phosphor can be a key for the phosphor converted w-LEDs for warm white light emission.