The Evidence for Ferroelectricity on Magnetite Ceramics below the Verwey Transition
WU Yu-Qiang1, WU Hong-Ying2**, ZHAO Jie1,3, LU Cui-Min1, ZHANG Bao-Long1, LIU Qing-Suo1, MA Yong-Chang1,4
1School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 2Institute of Radiation Medicine, and Tianjin Key laboratory of Molecular Nuclear Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192 3Tianjin Key Lab for Photoelectric Materials and Devices, Tianjin 300384 4Key Laboratory of Display Materials and Photoelectric Devices (Ministry of Education), Tianjin University of Technology, Tianjin 300384
The Evidence for Ferroelectricity on Magnetite Ceramics below the Verwey Transition
WU Yu-Qiang1, WU Hong-Ying2**, ZHAO Jie1,3, LU Cui-Min1, ZHANG Bao-Long1, LIU Qing-Suo1, MA Yong-Chang1,4
1School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 2Institute of Radiation Medicine, and Tianjin Key laboratory of Molecular Nuclear Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192 3Tianjin Key Lab for Photoelectric Materials and Devices, Tianjin 300384 4Key Laboratory of Display Materials and Photoelectric Devices (Ministry of Education), Tianjin University of Technology, Tianjin 300384
摘要We report the temperature- and frequency-dependent dielectric spectrum of magnetite ceramic single phase samples at 77.4–300 K and 200 Hz–1 MHz. In temperature-dependent dc resistivity, the sharp transition expected in single crystals is much suppressed. At higher temperatures, the grain boundaries contribute to the relaxation process. Below 120 K, the temperature-dependent dielectric constant reveals a weak broadened peak as cooling, from our analysis this behavior may be intrinsically correlated with the charge ordering of Fe3+ and Fe2+. Under a relatively low dc bias at 77.4 K, the polarization of the magnetite ceramic decreases, while under a much stronger electrical field, the dielectric spectrum in the lower frequency region is suppressed remarkably for the excitation of carriers bounded by grain boundaries.
Abstract：We report the temperature- and frequency-dependent dielectric spectrum of magnetite ceramic single phase samples at 77.4–300 K and 200 Hz–1 MHz. In temperature-dependent dc resistivity, the sharp transition expected in single crystals is much suppressed. At higher temperatures, the grain boundaries contribute to the relaxation process. Below 120 K, the temperature-dependent dielectric constant reveals a weak broadened peak as cooling, from our analysis this behavior may be intrinsically correlated with the charge ordering of Fe3+ and Fe2+. Under a relatively low dc bias at 77.4 K, the polarization of the magnetite ceramic decreases, while under a much stronger electrical field, the dielectric spectrum in the lower frequency region is suppressed remarkably for the excitation of carriers bounded by grain boundaries.
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2011, Vol. 28 
