Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8571, Japan.
Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8571, Japan.
Sci Rep. 2017 Mar 2;7:43791. doi: 10.1038/srep43791.
The chemical substitution of a transition metal (M) is an effective method to improve the functionality of a material, such as its electrochemical, magnetic, and dielectric properties. The substitution, however, causes local lattice distortion because the difference in the ionic radius (r) modifies the local interatomic distances. Here, we systematically investigated the local structures in the pure (x = 0.0) and mixed (x = 0.05 or 0.1) layered oxides, Na(MM')O (M and M' are the majority and minority transition metals, respectively), by means of extended X-ray absorption fine structure (EXAFS) analysis. We found that the local interatomic distance (d) around the minority element approaches that around the majority element to reduces the local lattice distortion. We further found that the valence of the minority Mn changes so that its ionic radius approaches that of the majority M.
过渡金属（M）的化学取代是改善材料功能的有效方法，例如其电化学、磁性和介电性能。然而，取代会导致局部晶格畸变，因为离子半径（r）的差异会改变局部原子间距离。在这里，我们通过扩展 X 射线吸收精细结构（EXAFS）分析，系统地研究了纯（x=0.0）和混合（x=0.05 或 0.1）层状氧化物 Na（MM'）O 中的局部结构，其中 M 和 M'分别为多数和少数过渡金属。我们发现，少数元素周围的局部原子间距离（d）接近多数元素，以减小局部晶格畸变。我们还发现，少数 Mn 的价态发生变化，使其离子半径接近多数 M 的离子半径。
