Europium-doped borosilicate glasses were prepared by melt-quenching procedure in the air.The mixed valence of Eu 2＋ and Eu 3＋ was identified by photoluminescence spectrum and electron paramagnetic resonance（EPR）.The existence of mixed valence was observed owing to the unequivalent substitution and de-polymerization network of the as-prepared borosilicate glasses.The variation of the glass composition in B 2 O 3 /BaO ratios changed the stability of the Eu 3＋ ions distinctly.In particular,as-prepared borosilicate glasses exhibited a tri-wavelength light excitable spectra centered at 397,466 and 534 nm to give the broadened orange-red emission at around 592 and 617 nm,due to supersensitive transitions of Eu 3＋ ions.This simultaneous tri-wavelength excitation happened to correspond with the emitting wavelength from near ultraviolet,blue AlInGaN chips and that from YAG：Ce 3＋.The total quantum yield（QY） of the Eu-doped glasses under 466 nm excitation was evaluated to be 10%,potentially providing a versatile combination with the europium-doped borosilicate glasses for red component addition to improve the quality of white light.
Yellow-emitting BCNO phosphors,applied for white light-emitting-diodes（LEDs）,were synthesized by a facile microwave heating route at lower temperature within short duration.The prepared BCNO phosphors exhibited amorphous form and tunable yellow emission in the range of 510–550 nm under the excitation of 450-nm blue light.The effects of carbon content on the photoluminescence properties for these BCNO phosphors and their application performances in white LEDs were investigated in detail.The demonstrated microwave synthesis route is promising in preparing low-cost phosphors,and the prepared BCNO phosphor may find potential application in blue-based white LEDs.
