Polymorphism and Oxide Ion Migration Pathways in Fluorite-Type Bismuth Vanadate, Bi46V8O89

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• 作者：Xiaojun Kuang ; Julia L. Payne ; James D. Farrell ; Mark R. Johnson ; Ivana Radosavljevic Evans
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：June 12, 2012
• 年：2012
• 卷：24
• 期：11
• 页码：2162-2167
• 全文大小：376K
• 年卷期：v.24,no.11(June 12, 2012)
• ISSN：1520-5002

文摘

We report the synthesis, structural characterization, and ionic conductivity measurements for a new polymorph of bismuth vanadate Bi₄₆V₈O₈₉, and an ab initio molecular dynamics study of this oxide ion conductor. Structure determination was carried out using synchrotron powder X-ray and neutron diffraction data; it was found that 尾-Bi₄₆V₈O₈₉ crystallizes in space group C2/m and that the key differences between this and the previously reported 伪-form are the distribution of Bi and V cations and the arrangement of the VO₄ coordination polyhedra in structure. 尾-Bi₄₆V₈O₈₉ exhibits good oxide ion conductivity, with 蟽 = 0.01鈥?.1 S/cm between 600 and 850 掳C, which is about an order of magnitude higher than yttria stabilized zirconia. The ab initio molecular dynamics simulations suggest that the ion migration pathways include vacancy diffusion through the Bi鈥揙 sublattice, as well as the O2鈥?/sup> exchanges between the Bi鈥揙 and the V鈥揙 sublattices, facilitated by the variability of the vanadium coordination environment and the rotational freedom of the VO_x coordination polyhedra.

Keywords:

Oxide ion conductors; bismuth vanadates; X-ray and neutron diffraction; AIMD simulations