Powder Synthesis and Photoluminescent Properties of Yellow-emitting Ba_5Si11Al_7N_(25):Eu~（2+） phosphors for White Light-Emitting Diodes

摘要

The single-particle-diagnosis approach is a facile and efficient method to develop novel luminescentmaterials for solid state lighting. The most critical issue for this method is achieving large-scale industrialproduction of powder from a single crystal[1]. The novel nitridoalumosilicate phosphor Ba_5Si11Al_7N_(25):Eu~(2+)was discovered by the single-particle-diagnosis method[2]. Differing from most phosphors, the phase-purepowder of Ba_5Si11Al_7N_(25):Eu~(2+) cannot be obtained by firing the starting materials with the stoichiometriccomposition of its single crystal. In this work, almost-pure phase Ba_5Si11Al_7N_(25):Eu~(2+) powder was obtainedby optimizing the chemical composition at 1900°C for 2 hours under 0.92 MPa N_2. Upon excitation withviolet light (400nm), the as-prepared sample showed a broad emission band with a maximum emissionpeak at ~566 nm and a full width at half-maximum (FWHM) of 88 nm. The excitation spectrum rangedfrom 350 to 550 nm, which indicated that the Ba_5Si11Al_7N_(25):Eu~(2+) phosphor could be efficiently excited withboth near-UV LEDs and blue LEDs. In addition, weak thermal quenching was observed in theBa_5Si11Al_7N_(25):1%Eu~(2+) phosphor. When the temperature increased up to 150 °C, the integrated emissionintensity of the Ba_5Si11Al_7N_(25):1%Eu~(2+) phosphor still maintained 94% of the initial intensity at 30 °C. TheBa_5Si11Al_7N_(25):Eu~(2+) promises to be a new commercial phosphor comparable to YAG:Ce3+ for whitelight-emitting diodes.