Electrical property of nanocrystalline ¦Ã-Fe₂O₃ under high pressure

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• 作者：Dongmei Zhang^a ; ^b ; ^{zhangdongmei1998@yahoo.com.cn} ; Chunhe Zang^a ; Yongsheng Zhang^a ; Yonghao Han^b ; Chunxiao Gao^b ; ^{cxgao599@yahoo.com.cn} ; Yanxin Yang^a ; Ke Yu^c
• 关键词：High pressure ; Electronic transport ; Phase transition
• 刊名：Physica B
• 出版年：2012
• 出版时间：15 March 2012
• 年：2012
• 卷：407
• 期：6
• 页码：1044-1046
• 全文大小：388 K

文摘

Using a microcircuit fabricated on a diamond anvil cell, in situ conductivity measurements on nanophase (NP) ¦Ã-Fe₂O₃ are obtained under high pressure. For NP ¦Ã-Fe₂O₃, the abrupt increase in electrical conductivity occurs at a pressure of 21.3 GPa, corresponding to a transition from maghemite to hematite. Above 26.4 GPa, conductivity increases smoothly with increasing pressure. No distinct abnormal change is observed during decompression, indicating that transformation is irreversible. The temperature-dependence of the conductivity of NP ¦Ã-Fe₂O₃ was investigated at several pressures, indicating the electrical conductivity of the sample increases with increasing pressure and temperature, and that a remarkable phenomenon of discontinuity occurs at 400 K. The abnormal change is attributed to the electronic phase transitions of NP ¦Ã-Fe₂O₃ due to the variation of inherent cation vacancies. Besides, the temperature-dependence of the electrical conductivity displays semiconductor-like behavior before 33.0 GPa.