Department Chemie, Lehrstuhl für Anorganische Festkörperchemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (D), 81377 München, Germany.
Chemistry. 2010 Aug 16;16(31):9646-57. doi: 10.1002/chem.201000660.
The efficient green phosphor Ba(3)Si(6)O(12)N(2):Eu(2+) and its solid-solution series Ba(3-x)Sr(x)Si(6)O(12)N(2) (with x approximately = 0.4 and 1) were synthesized in a radio-frequency furnace under nitrogen atmosphere at temperatures up to 1425 degrees C. The crystal structure (Ba(3)Si(6)O(12)N(2), space group P3 (no. 147), a = 7.5218(1), c = 6.4684(1) A, wR2 = 0.048, Z = 1) has been solved and refined on the basis of both single-crystal and powder X-ray diffraction data. Ba(3)Si(6)O(12)N(2):Eu(2+) is a layer-like oxonitridosilicate and consists of vertex-sharing SiO(3)N-tetrahedra forming 6er- and 4er-rings as fundamental building units (FBU). The nitrogen atoms are connected to three silicon atoms (N3), while the oxygen atoms are either terminally bound (O1) or bridge two silicon atoms (O2) (numbers in superscripted square brackets after atoms indicate the coordination number of the atom in question). Two crystallographically independent Ba(2+) sites are situated between the silicate layers. Luminescence investigations have shown that Ba(3)Si(6)O(12)N(2):Eu(2+) exhibits excellent luminescence properties (emission maximum at approximately 527 nm, full width at half maximum (FWHM) of approximately 65 nm, low thermal quenching), which provides potential for industrial application in phosphor-converted light-emitting diodes (pc-LEDs). In-situ high-pressure and high-temperature investigations with synchrotron X-ray diffraction indicate decomposition of Ba(3)Si(6)O(12)N(2) under these conditions. The band gap of Ba(3)Si(6)O(12)N(2):Eu(2+) was measured to be 7.05+/-0.25 eV by means of X-ray emission spectroscopy (XES) and X-ray absorption near edge spectroscopy (XANES). This agrees well with calculated band gap of 6.93 eV using the mBJ-GGA potential. Bonding to the Ba atoms is highly ionic with only the 4p(3/2) orbitals participating in covalent bonds. The valence band consists primarily of N and O p states and the conduction band contains primarily Ba d and f states with a small contribution from the N and O p states.
在氮气气氛下，于射频炉中在高达 1425°C 的温度下合成了高效的绿色荧光体 Ba(3)Si(6)O(12)N(2):Eu(2+)及其固溶体系列 Ba(3-x)Sr(x)Si(6)O(12)N(2)(其中 x 约为 0.4 和 1)。根据单晶和粉末 X 射线衍射数据，解决并精修了晶体结构（Ba(3)Si(6)O(12)N(2)，空间群 P3（编号 147），a = 7.5218(1)，c = 6.4684(1)A，wR2 = 0.048，Z = 1）。Ba(3)Si(6)O(12)N(2):Eu(2+) 是一种层状的氧氮化物硅酸盐，由共用顶点的 SiO(3)N-四面体组成，形成 6er-和 4er-环作为基本结构单元（FBU）。氮原子连接到三个硅原子（N3），而氧原子要么是端接的（O1），要么桥接两个硅原子（O2）（原子上方带方括号的数字表示该原子的配位数）。两个结晶学上独立的 Ba(2+) 位位于硅酸盐层之间。荧光研究表明，Ba(3)Si(6)O(12)N(2):Eu(2+) 表现出优异的荧光性能（发射最大值约为 527nm，半峰全宽（FWHM）约为 65nm，热猝灭低），这为在磷光转换发光二极管（pc-LED）中的工业应用提供了潜力。同步辐射 X 射线衍射的原位高压高温研究表明，在这些条件下 Ba(3)Si(6)O(12)N(2)会分解。通过 X 射线发射光谱（XES）和 X 射线吸收近边光谱（XANES）测量，Ba(3)Si(6)O(12)N(2):Eu(2+) 的能带隙为 7.05+/-0.25eV。这与使用 mBJ-GGA 势计算得出的 6.93eV 的能带隙非常吻合。与 Ba 原子的键合高度离子化，只有 4p(3/2)轨道参与共价键。价带主要由 N 和 O p 态组成，导带主要包含 Ba d 和 f 态，N 和 O p 态有少量贡献。
