Li₇B₇Se₁₅: A novel selenoborate with a zeolite-like polymeric anion structure

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• 作者：Steffen Pü ; tz ; Matthias Dö ; ch ; Adrienne Hammerschmidt ; Arno Lindemann ; Hellmut Eckert ; Tom Nilges and Bernt Krebs
• 关键词：Selenoborates ; Boron ; Crystal structure ; Cation dynamic ; Lithium mobility
• 刊名：Solid State Sciences
• 出版年：2006
• 出版时间：July 2006
• 年：2006
• 卷：8
• 期：7
• 页码：764-772
• 全文大小：421 K

文摘

Compared to the hitherto known polymeric seleno- and perselenoborates a new and remarkable structural principle was realized in the lithium selenoborate Li₇B₇Se₁₅. The three dimensional anion sublattice is formed by entities of formal composition [B₇Se₁₃]⁵⁻. Additionally, isolated diselenide units and lithium cations are found in the structure. The connection pattern of the basic corner-sharing BSe₄-tetrahedra gives rise to this tetragonal structure hitherto unknown in both, oxidic and non-oxidic chalcogenoborate chemistry. A characteristic feature of the structure is an extensive system of channels facilitating ionic motion and providing different diffusion paths for the Li ions. This channel system offers several atom sites suitable for lithium cations. As expected, some Li positions are partially occupied and they show comparatively large anisotropic displacement ellipsoids which prove the mobility of the cations already at room temperature, indicating an above average ion conductivity in this chalcogenoborate. The new chalcogenoborate was prepared in a solid state reaction from lithium selenide, amorphous boron and selenium in evacuated carbon coated silica tubes at a temperature of 800 °C. Li₇B₇Se₁₅ crystallizes tetragonal, space group P4₂/nbc (no. 133) with a