Pressure-Induced Amorphization in Single-Crystal Ta2O5 Nanowires: A Kinetic Mechanism and Improved Electrical Conductivity

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• 作者：Xujie L眉 ; Qingyang Hu ; Wenge Yang ; Ligang Bai ; Howard Sheng ; Lin Wang ; Fuqiang Huang ; Jianguo Wen ; Dean J. Miller ; Yusheng Zhao
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 18, 2013
• 年：2013
• 卷：135
• 期：37
• 页码：13947-13953
• 全文大小：453K
• 年卷期：v.135,no.37(September 18, 2013)
• ISSN：1520-5126

文摘

Pressure-induced amorphization (PIA) in single-crystal Ta₂O₅ nanowires is observed at 19 GPa, and the obtained amorphous Ta₂O₅ nanowires show significant improvement in electrical conductivity. The phase transition process is unveiled by monitoring structural evolution with in situ synchrotron X-ray diffraction, pair distribution function, Raman spectroscopy, and transmission electron microscopy. The first principles calculations reveal the phonon modes softening during compression at particular bonds, and the analysis on the electron localization function also shows bond strength weakening at the same positions. On the basis of the experimental and theoretical results, a kinetic PIA mechanism is proposed and demonstrated systematically that amorphization is initiated by the disruption of connectivity between polyhedra (TaO₆ octahedra or TaO₇ bipyramids) at the particular weak-bonding positions along the a axis in the unit cell. The one-dimensional morphology is well-preserved for the pressure-induced amorphous Ta₂O₅, and the electrical conductivity is improved by an order of magnitude compared to traditional amorphous forms. Such pressure-induced amorphous nanomaterials with unique properties surpassing those in either crystalline or conventional amorphous phases hold great promise for numerous applications in the future.