Pressure-Induced Crystallization and Characterization of the Tin Borate -SnB4O7

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• 作者：Johanna S. Knyrim ; Falko M. Schappacher ; Rainer P&ouml ; ttgen ; J&ouml ; rn Schmedt auf der Gü ; nne ; Dirk Johrendt ; Hubert Huppertz
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：January 23, 2007
• 年：2007
• 卷：19
• 期：2
• 页码：254 - 262
• 全文大小：434K
• 年卷期：v.19,no.2(January 23, 2007)
• ISSN：1520-5002

文摘

In the last years, several investigations were performed in the ternary system Sn-B-O as a simplifiedvariant of the tin-based amorphous composite oxide (TCO), a material in use as negative electrode oflithium-ion rechargeable batteries. All compounds in this system are glasses, so the synthesis of crystallineapproximands for a more detailed structural investigation would be favorable. The use of high-pressure/high-temperature conditions (7.5 GPa and 1100 ges/entities/deg.gif">C; Walker-type multianvil apparatus) led to the synthesisof the first crystalline tin borate ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-SnB₄O₇. The single-crystal structure determination of ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-SnB₄O₇ showedPmn2₁, a = 1086.4(2) pm, b = 444.80(9) pm, c = 423.96(8) pm, Z = 2, R₁ = 0.0155, and wR₂ = 0.0324(all data). In contrast to the isotypic phases MB₄O₇ (M = Sr, Pb, Eu, ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-Ca, and ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-Hg), the position ofthe tin atom in ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-SnB₄O₇ is influenced by the existence of a stereochemically active lone pair. Furthermore,we report on thermoanalytical aspects (DTA-TG and temperature-resolved in situ powder diffraction),DFT calculations, IR spectroscopy, Mössbauer spectroscopic results, and solid-state NMR investigationson ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-SnB₄O₇. The latter method allows us to make a general differentiation of Sn²⁺ and Sn⁴⁺ in Sn-Osystems on the basis of well-separated ^117/119Sn chemical shifts.