A (3 + 3)-Dimensional 鈥淗ypercubic鈥?Oxide-Ionic Conductor: Type II Bi2O3鈥揘b2O5

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• 作者：Chris D. Ling ; Siegbert Schmid ; Peter E. R. Blanchard ; Vaclav Pet艡铆膷ek ; Garry J. McIntyre ; Neeraj Sharma ; Andrey Maljuk ; Aleksey A. Yaremchenko ; Vladislav V. Kharton ; Matthias Gutmann ; Ray L. Withers
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：May 1, 2013
• 年：2013
• 卷：135
• 期：17
• 页码：6477-6484
• 全文大小：517K
• 年卷期：v.135,no.17(May 1, 2013)
• ISSN：1520-5126

文摘

The high-temperature cubic form of bismuth oxide, 未-Bi₂O₃, is the best intermediate-temperature oxide-ionic conductor known. The most elegant way of stabilizing 未-Bi₂O₃ to room temperature, while preserving a large part of its conductivity, is by doping with higher valent transition metals to create wide solid-solutions fields with exceedingly rare and complex (3 + 3)-dimensional incommensurately modulated 鈥渉ypercubic鈥?structures. These materials remain poorly understood because no such structure has ever been quantitatively solved and refined, due to both the complexity of the problem and a lack of adequate experimental data. We have addressed this by growing a large (centimeter scale) crystal using a novel refluxing floating-zone method, collecting high-quality single-crystal neutron diffraction data, and treating its structure together with X-ray diffraction data within the superspace symmetry formalism. The structure can be understood as an 鈥渋nflated鈥?pyrochlore, in which corner-connected NbO₆ octahedral chains move smoothly apart to accommodate the solid solution. While some oxide vacancies are ordered into these chains, the rest are distributed throughout a continuous three-dimensional network of wide 未-Bi₂O₃-like channels, explaining the high oxide-ionic conductivity compared to commensurately modulated phases in the same pseudobinary system.