A new yellowish green NaAl(SiO4):Eu2+ phosphor for UV-LED using a liquid phase precursor process

Abstract

Yellowish green NaSiAlO4 : Eu-x (x = 0.02, 0.05, 0.07, 0.1 and 0.13) phosphors for UV-LEDs were synthesized using a Liquid Phase Precursor process (LPP). In this process, the NaSiAlO4 : Eu-x phosphors were obtained using a cellulose pulp as a template with a micro fiber structure. Aqueous solutions of the raw materials were impregnated into the cellulose pulp, which was then dried, calcined rapidly at 1000 degrees C and post fired at 1100-1250 degrees C under a reducing atmosphere (95% N-2 + 5% H-2). The phosphors obtained were examined by X-ray diffraction, photoluminescence and field emission scanning electron microscopy analyses. A new yellowish green phosphor was produced at 1100-1200 degrees C. The NaSiAlO4 : Eu2+ phosphor had a nepheline hexagonal structure with space group P6(1) according to the JCPDS card (No. 79-0993). The phosphor fired at 1200 degrees C had a particle size of approximately similar to 4 mu m. The excitation spectrum was located at 250-475 nm and the emission spectrum showed a yellowish green light with the strongest emission at 551 nm.