Syntheses and Characterizations of New Eu-Ce Codoped LaSrSiO3N Phosphors for LEDs

New luminescent oxynitridosilicates doped with Eu2+ and Ce3+ have been synthesized by solid state reaction method at 1450oC. The host has the general formula La1-ySr1-xSiO3N: (yCe3+, xEu2+), which presents greenish-yellow or orange photoluminescence under UV/blue excitation. Remarkable long wavelength emissions centered above 565 nm were observed for the Ce3+ activated oxynitridosilicates, with compositions LaSrSiO3N:0.02Ce3+, and LaSrSiO3N:(0.02Ce3+, 0.02Eu2+) for 598 nm due to a significant amount of energy transfer from Ce3+ ions to Eu2+ ions. By combining the title LaSrSiO3N:(Ce3+, Eu2+) phosphors with the 450 nm InGaN chip, a broad range of white light with correlated color temperatures of ~3500 K and color-rendering index of 92 can be generated, demonstrating their promising practical applicability to the warm-white light-emitting diodes.