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The crystal structure and the photoluminescence properties of novel green Ba 4-y Eu y Si 6 O 16-3x/2 N x  phosphors were investigated. The electronic structures of the Ba 4 Si 6 O 16  host were calculated by first principles pseudopotential method based on density functional theory. The results reveal that the top of the valence bands are dominated by O-2p states hybridized with Ba-6s and Si-3p states, while the conduction bands are mainly determined by Ba-6s states for the host, which is an insulator with a direct energy gap of 4.6 eV at Γ. A small amount of nitrogen can be incorporated into the host to replace oxygen and forms Ba 4-y Eu y Si 6 O 16-3x/2 N x  solid solutions crystallized in a monoclinic (space group  P 2 1 /c, Z = 2) having the lattice parameters  a  = 12.4663(5) Å,  b  = 4.6829(2) Å,  c  = 13.9236(6) Å, and  β  = 93.61(1)°, with a maximum solubility of nitrogen at about x = 0.1. Ba 4 Si 6 O 16-3x/2 N x :Eu 2+  exhibits efficient green emission centered at 515–525 nm varying with the Eu 2+  concentration when excited under UV to 400 nm. Furthermore, the incorporation of nitrogen can slightly enhance the photoluminescence intensity. Excitation in the UV-blue spectral range (λ exc  = 375 nm), the absorption and quantum efficiency of Ba 4-y Eu y Si 6 O 16-3x/2 N x  (x = 0.1, y = 0.2) reach about 80% and 46%, respectively. Through further improvement of the thermal stability, novel green phosphor of Ba 4-y Eu y Si 6 O 16-3x/2 N x  is promising for application in white UV-LEDs.

Crystal and Electronic Structures, Photoluminescence Properties of Eu2+-Doped Novel Oxynitride Ba4Si6O16-3x/2Nx