Direct Measurement of Electronic Band Structures at Oxide Grain Boundaries
Direct Measurement of Electronic Band Structures at Oxide Grain Boundaries
复制标题
氧化物晶界处电子能带结构的直接测量
DOI：
10.1021/acs.nanolett.9b05298
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发表时间：
2020
期刊：
影响因子：
10.8
通讯作者：
Ikuhara Yuichi
中科院分区：
文献类型：
--
作者：
Wei Jiake;Ogawa Takafumi;Feng Bin;Yokoi Tatsuya;Ishikawa Ryo;Kuwabara Akihide;Matsunaga Katsuyuki;Shibata Naoya;Ikuhara Yuichi
晶界 (GB) 调节多晶材料的宏观特性，因为它们具有与块体不同的原子和电子结构。尽管对GB原子结构的理解取得了进展，但对局域电子能带结构的了解仍然缺乏。在这里，我们通过扫描透射电子显微镜和价电子能量损失谱（EELS）对α-Al2O3中四种典型晶界的原子结构和带隙进行了实验表征。研究发现，与块体的带隙 8.8 eV 相比，GB 的带隙窄了 0.5-2.1 eV。通过将磁芯损耗 EELS 与第一原理计算相结合，我们阐明带隙减小与晶界处 Al 和 O 离子配位数的减少直接相关。这些结果提供了对晶界局部原子和电子能带结构的深入了解，并展示了一种新颖的晶体缺陷电子结构分析。
Grain boundaries (GBs) modulate the macroscopic properties in polycrystalline materials because they have different atomic and electronic structures from the bulk. Despite the progress on the understanding of GB atomic structures, knowledge of the localized electronic band structures is still lacking. Here, we experimentally characterized the atomic structures and the band gaps of four typical GBs in α-Al2O3by scanning transmission electron microscopy and valence electron energy-loss spectroscopy (EELS). It was found that the band gaps of the GBs are narrowed by 0.5–2.1 eV compared with that of 8.8 eV in the bulk. By combing core-loss EELS with first-principles calculations, we elucidated that the band gap reductions directly correlate with the decrease of the coordination numbers of Al and O ions at the GBs. These results provide in-depth understanding between the local atomic and electronic band structures for GBs and demonstrate a novel electronic-structure analysis for crystalline defects.