Eu2+, Tb3+, Mn2+Triactivated Ba3MgSi2O8Red-Emitting Phosphors for Near Ultraviolet Lighting Emitting Diodes

A series of Ba 2.99-x Mg 0.9 Si 2 O 8 (BMS):0.01Eu 2+ , xTb 3+ , 0.1Mn 2+ phosphors (x = 0–0.3) were synthesized via high-temperature solid-state reaction method, and the influence of Tb 3+ content on luminescence properties of the phosphors were investigated by photoluminescence (PL) and micro cathodoluminescence (μ-CL). Three emission bands centered at 437, 505 and 620 nm were observed for Tb 3+ free sample. The doping of Tb 3+ enhanced the red emission of Mn 2+ at 620 nm, and decreased the intensity of the blue and green emission bands simultaneously. At a Tb 3+ content of x = 0.2, the intensity ratio of red to blue emission was enhanced by a factor of 2.4 relative to that of x = 0, and meanwhile the green emission became nearly negligible. A combined analysis with fluorescence microscope, μ-CL, EDAX and XRD manifested that the green emission was contributed by Ba 2 SiO 4 :Eu 2+ like impurity, whose formation was inhibited with the incorporation of Tb 3+ . The increased red/blue ratio, on the one hand, was attributed to the introduction of an additional energy transfer (ET) route, i.e. Eu 2+ →Tb 3+ →Mn 2+ , besides the Eu 2+ →Mn 2+ route so as to enhance ET probability from Eu 2+ to Mn 2+ , as evidenced by PL excitation measurements, and on the other hand was ascribed to improvement of phase purity of glaserite-type BMS.