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Cr掺杂锐钛矿型TiO2(001)薄膜中Cr原子的直接观测
王兵
作者单位E-mail
王兵 中国科技大学微尺度物质国家实验室 bwang@ustc.edu.cn 
摘要:
掺杂元素的成像对于理解TiO2掺杂薄膜的光催化活性是至关重要的。然而,如何在原子尺度上表征掺杂原子与TiO2晶格之间的相互关联性仍然是一项挑战性工作。本文中我们利用高角环形暗场像/环形明场像扫描透射电镜(HAADF/ABF-STEM)结合电子能量损失谱(EELS)从[100]晶向上对锐钛矿型TiO2(001)薄膜中掺杂的单个铬原子进行了直接成像。结果表明,Cr掺杂原子同时占据TiO2晶格中的取代位和填隙位,而其可以用具有原子级分辨的电子能量损失谱元素面分布图(EELS mapping)来成像识别,但在HAADF/ABF-STEM图像中未能被看到。大部分的Cr掺杂原子更倾向于取代TiO2晶格中的Ti原子。这些结果在原子尺度上为Cr掺杂TiO2薄膜的掺杂构型提供了直接的证据,同时也表明电子能量损失谱元素面分布图在对掺杂材料的结构表征是个非常出色的技术。
关键词:  Anatase TiO2, Cr dopants, Scanning Transmission Electron Microscope (STEM), Electron Energy Loss Spectroscopy (EELS), Pulsed Laser Deposition (PLD)
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Direct view the Cr atoms doped in Anatase TiO2(001) thin ?lm
wangbing
Abstract:
Imaging the doping elements is critical for understanding the photocatalytic activity of doped TiO2 thin film. But it is still a challenge to characterize the interactions between the dopants and the TiO2 lattice at the atomic level. Here, we use High Angle Annular Dark-Field/Annular Bright-Field Scanning Transmission Electron Microscope (HAADF/ABF-STEM) combined with Electron Energy Loss Spectroscopy (EELS) to directly image the individual Cr atoms doped in anatase TiO2(001) thin film from [100] direction. The Cr dopants, which are clearly imaged through the atomic-resolution EELS mappings while can not be seen by HADDF/ABF-STEM, occupy both the substitutional sites of Ti atoms and the interstitial sites of TiO2 matrix. Most of them preferentially locate at the substitutional sites of Ti atoms. These results provide the direct evidence for the doping structure of Cr-doped A-TiO2 thin film at the atomic level and also prove the EELS mapping is an excellent technique for characterizing the doped materials.
Key words:  Anatase TiO2, Cr dopants, Scanning Transmission Electron Microscope (STEM), Electron Energy Loss Spectroscopy (EELS), Pulsed Laser Deposition (PLD)