Effect of average and local structures on lithium ion conductivity in La2/3-xLi3xTiO3
Effect of average and local structures on lithium ion conductivity in La2/3-xLi3xTiO3
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DOI：
10.1039/c0jm04372a
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发表时间：
2011-01-01
影响因子：
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通讯作者：
Ogumi, Zempachi
中科院分区：
文献类型：
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作者：
Okumura, Toyoki;Ina, Toshiaki;Ogumi, Zempachi
为了研究锂离子传导钙钛矿氧化物La2/3-xLi3xTiO3 (x = 0.06-0.15) (LLT)的锂离子传导机制，对其平均结构、局部结构和锂离子电导率进行了分析。我们应用 Rietveld 分析和 X 射线衍射来讨论 LLT 的平均结构，其中 A 位离子沿斜方晶格的 c 轴排列为无序（高温相，HT）和有序（低温相，LT）A 位离子。还测量了同步加速器 X 射线吸收精细结构 (XAFS) 分析，以考虑局部结构。由A位离子排序或锂离子浓度变化引起的锂离子迁移差异可以通过锂与周围离子之间的原子位置和库仑相互作用得到很好的解释。局部原子间距离通过扩展 XAFS (EXAFS) 以及反映感兴趣离子周围局部畸变的 Debye Waller 因子进行估计。对这些局部结构特征和锂离子传导的活化能的考虑表明，锂离子传导性受到锂离子和钛离子之间的库仑斥力和/或由四个氧离子组成的锂离子通道中的瓶颈变形的控制。
In order to investigate lithium ion conduction mechanism of the lithium ion-conducting perovskite oxides, La2/3-xLi3xTiO3 (x = 0.06-0.15) (LLT), their average structure, local structure and lithium ion conductivity were analyzed. We applied Rietveld analysis with X-ray diffraction for discussing the average structure of LLT with disordered (high temperature phase, HT) and ordered (low temperature phase, LT) A-site ion arrangements along the c-axis of its orthorhombic lattice. Synchrotron X-ray absorption fine structure (XAFS) analysis was also measured for considering local structures. Differences for lithium ion migration caused by A-site ion ordering or change of lithium ion concentration are well-explained by the atomic positions and Coulombic interactions among the lithium and surrounding ions. The local inter-atomic distances were estimated by extended XAFS (EXAFS), as well as Debye Waller factors that reflect local distortion around the ions of interest. Consideration on these local structure features and the activation energy for the lithium ion conduction indicates that the lithium ion conductivity is governed by the Coulombic repulsion force between the lithium ion and the titanium ion, and/or the bottleneck distortion in the lithium ion channels consisted of four oxygen ions.