Synthesis, Structure, and Luminescence Properties of K2Ba7Si16O40:Eu2+ for White Light Emitting Diodes

In this paper, a novel divalent europium-doped green emitting blue convertible K2Ba7Si16O40:Eu2+ phosphor has been synthesized successfully via high-temperature solid-state reaction. The structure of K2Ba7Si16O40:Eu2+ has been refined on the basis of X-ray powder diffraction by Rietveld refinement method, which consists of two infinite dimensional layers of corner-sharing [SiO4] tetrahedral parallel to (201) linked together through eight-coordinate K and seven- and nine-coordinate Ba atoms. Under excitation of blue light, the K2Ba7Si16O40:Eu2+ phosphor emits a strong green emission band peaking at 500 nm. The concentration quenching mechanism of the Eu2+ ion was discussed and the critical distance was calculated. Furthermore, the phosphor exhibits high quantum efficiency and good thermal stability, indicating that the K2Ba7Si16O40:Eu2+ phosphor can serve as an effective green emitting candidate for blue light down-conversion white light emitting diodes.