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

Materials

Yuanqiang Li²  Yuan Fang²  Naoto Hirosaki¹  Rong-Jun Xie¹  Lihong Liu¹  Takashi Takeda¹ 

[1] Nitride Particle Group, Nano Ceramics Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan; E-Mails:;College of Materials Science and Engineering, Nanjing University of Technology, New Model Road 5, Nanjing, Jiangsu 210009, China; E-Mails:

关键词: barium silicon oxynitride;    europium;    crystal structure;    electronic structure;    luminescence properties;    thermal quenching;   

DOI  :  10.3390/ma3031692

来源: mdpi

【 摘 要 】

The crystal structure and the photoluminescence properties of novel green Ba_4-yEu_ySi₆O_16-3x/2N_x phosphors were investigated. The electronic structures of the Ba₄Si₆O₁₆ 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-yEu_ySi₆O_16-3x/2N_x solid solutions crystallized in a monoclinic (space group P2₁/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. Ba₄Si₆O_16-3x/2N_x:Eu²⁺ exhibits efficient green emission centered at 515–525 nm varying with the Eu²⁺ 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-yEu_ySi₆O_16-3x/2N_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-yEu_ySi₆O_16-3x/2N_x is promising for application in white UV-LEDs.

【 授权许可】

CC BY   
© 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.