A promising blue-green emitting phosphor for white light-emitting diodes prepared by sol-gel method

摘要

(Ba_(2-x)Eu_x)ZnSi_2O_7 blue-green phosphors were prepared by a sol-gel (SG) process. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravi-metric analysis (TG). The properties of the resulting phosphors were characterized by photoluminescence (PL) spectroscopy. The shape and size of the sample were observed by transmission electron microscopy (TEM). The results of TG and XRD indicate that the (Ba_(2-x)Eu_x)ZnSi_2O_7 phosphors crystallize completely at 900 °C. The emission spectrum shows a single band centered at 500 nm, which corresponds to the 4f~6 5d~1 -> 4f~7 transition of Eu~(2+). The excitation spectrum is a broad band extending from 260 to 465 nm, which matches the emission of ultraviolet light-emitting diodes (UV-LEDs). The critical quenching concentration of Eu~(2+) in Ba_2ZnSi_2O_7:Eu~(2+) phosphor is about 0.10mol. The value of the critical transfer distance is calculated as 15.1 A. The corresponding concentration quenching mechanism is verified to be the electric multipole-multipole interaction.