DOE OSTI2018
Highlights: • The wide range of the emission spectra of Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}{sub 0.03} were clarified by Van Uitert equation and the crystal field strength equation. • The Mn{sup 2+} and Tb{sup 3+} had enhanced the total PL intensity up to 30% comparing to only Eu{sup 2+} doped phosphor. • W-LEDs using Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}{sub 0.03}, Mn{sup 2+}{sub 0.06}, Tb{sup 3+}{sub 0.06} and BAM: Eu{sup 2+} resulted in an excellent CRI of 89 and CIE coordinates of (0.3463, 0.3898). - Abstract: A series of single phased phosphors Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}, Mn{sup 2+}, Tb{sup 3+} 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{sup 7}→ 4f{sup 6}5d{sup 1} electronic transition of the Eu{sup 2+} ions. Under NUV excitation, the broad yellow emission was obtained from tri-activated Sr{sub 8}MgLa(PO{sub 4}){sub 7} phosphors via combining three emission bands centered at 500, 550, and 600 nm contributed by Eu{sup 2+}, Tb{sup 3+} and Mn{sup 2+}, respectively. The optimized concentrations of Mn{sup 2+} and Tb{sup 3+} were 6 mol%, respectively, which enhanced the total PL intensity up to 30% comparing to only Eu{sup 2+} doped phosphor. Moreover, the quantum efficiency of Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}, Mn{sup 2+}, Tb{sup 3+} phosphor had achieved up to 52%. The combination of a NUV chip with compound of Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}, Mn{sup 2+}, Tb{sup 3+} and BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} achieved tunable w-LEDs with high CRI. The results suggest that this single phased Sr{sub 8}MgLa(PO{sub 4}){sub 7}: Eu{sup 2+}, Mn{sup 2+}, Tb{sup 3+} phosphor can be a key for the phosphor converted w-LEDs for warm white light emission.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗