Structure elucidation of BaSi₂O₂N₂ – A host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs

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• 作者：Juliane A. Kechele ; Oliver Oeckler ; Florian Stadler ; Wolfgang Schnick
• 关键词：Oxonitridosilicate ; Electron diffraction ; Structure elucidation ; Neutron diffraction ; Powder diffraction
• 刊名：Solid State Sciences
• 出版年：2009
• 出版时间：February 2009
• 年：2009
• 卷：11
• 期：2
• 页码：537-543
• 全文大小：547 K

文摘

BaSi₂O₂N₂ is a promising host lattice for rare-earth doped luminescent materials in phosphor-converted (pc)-LEDs. Applying a combined approach, its orthorhombic average structure (space group Cmcm (no. 63), a = 14.3902(3) Å, b = 5.3433(1) Å, c = 4.83256(7) Å and V = 371.58(2) Å³, Z = 4) has been elucidated by electron diffraction and structure solution from X-ray and neutron powder diffraction data with subsequent Rietveld refinement (wRp = 0.0491 for X-ray data). The structure contains layers of highly condensed SiON₃ tetrahedra with O terminally bound to Si. The Ba²⁺ ions are situated between the layers and are surrounded by a cuboid of O atoms capped by two N atoms. In the structure, there is only one Ba site and one Si site, respectively, which is in accordance with a single sharp ²⁹Si NMR signal observed at −52.8 ppm typical for SiON₃ tetrahedra in MSi₂O₂N₂ type oxonitridosilicates. Lattice energy calculations support the results of the structure determination.