Atomic and electronic band structures of Ti-doped Al2O3 grain boundaries
Atomic and electronic band structures of Ti-doped Al2O3 grain boundaries
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Ti掺杂Al2O3晶界的原子和电子能带结构
DOI：
10.1016/j.actamat.2020.10.018
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发表时间：
2020
期刊：
影响因子：
9.4
通讯作者：
Yuichi Ikuhara
中科院分区：
文献类型：
--
作者：
Chuchu Yang;Bin Feng;Wei Jiake;Eita Tochigi;Saki Ishihara;Naoya Shibata;Yuichi Ikuhara
掺杂是改变多晶材料性能最流行的策略之一，因为掺杂剂更喜欢在晶界（GB）处偏析并影响材料的结构和电子性能。了解掺杂剂如何在晶界上分离以及它们如何影响最终的晶界特性至关重要。在这里，我们通过原子分辨率扫描透射电子显微镜（STEM）、能量色散X射线光谱（EDXS）和价电子能量损失光谱（EELS）对α-Al 2 O 3 中Ti掺杂Σ7 {4 5´ 10}和Σ7 {2 3´ 10} GBs的原子结构和电子能带结构进行了实验表征。研究发现，由于Ti 3+ 和Al 3+ 之间的离子尺寸不匹配，Ti 优先在特定原子位点偏析，从而导致两种晶界中的结构转变。直接价态EELS测量揭示了Ti 3+ 离子的偏析在Al 2 O 3 GBs的带隙内引入了杂质带。这些结果提供了对钛掺杂晶界的局部原子和电子能带结构的深入了解。
Doping is one of the most popular strategies to modify the properties of polycrystalline materials, because the dopants prefer to segregate at the grain boundaries (GBs) and influence the structural and electronic properties of the materials. Understanding how dopants segregate at GBs and how they affect the resultant GB properties are essential. Here, we experimentally characterized the atomic structures and the electronic band structures of Ti-doped Σ7 {4 5¯ 10} and Σ7 {2 3¯ 10} GBs in α-Al 2 O 3 by atomic resolution scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDXS) and valence electron energy-loss spectroscopy (EELS). It was found that Ti preferentially segregated at specific atom sites driven by ionic size mismatch between Ti 3+ and Al 3+, which leads to structural transformations in both GBs. Direct valence EELS measurement revealed the segregation of Ti 3+ ions introduces impurity band within the bandgap in Al 2 O 3 GBs. These results provide an in-depth understanding of the local atomic and electronic band structures for Ti-doped GBs.