| Magnetic Behaviour and Heating Effect of Fe3O4 Ferrofluids Composed of Monodisperse Nanoparticles |
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| 作者姓名： | 张丽英 窦永华 张玲 古宏晨 |
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| 作者单位： | National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Films and Microfabrication of MOE, Research Institute of Micro and Nano Science and Technology, Shanghai diaotong University, Shanghai 200030 |
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| 基金项目： | Supported by the National High Technology Research and Development Programme of China under Grant No 2005AA302H10. |
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| 摘 要： | Fe3O4 ferrofluids containing monodisperse Fe3O4 nanoparticles with different diameters of 8, 12, 16 and 18nm are prepared by using high-temperature solution phase reaction. The particles have single crystal structures with narrow size distributions. At room temperature, the 8-nm ferrofluid shows superparamagnetic behaviour, whereas the others display hysteresis properties and the coercivity increases with the increasing particle size. The spin glass-like behaviour and cusps near 190K are observed on all ferrofluids according to the temperature variation of field-cooled （FC） and zero-field-cooled （ZFC） magnetization measurements. The cusps are found to be associated with the freezing point of the solvent. As a comparison, the ferrofluids are dried and the FC and ZFC magnetization curves of powdery samples are also investigated. It is found that the blocking temperatures for the powdery samples are higher than those for their corresponding ferrofluids. Moreover, the size dependent heating effect of the ferrofluids is also investigated in ac magnetic field with a frequency of 55 kHz and amplitude of 200 Oe.
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| 关 键 词： | 纳米离子 铁磁流体 热效应 磁特性 |
| 收稿时间： | 2006-9-26 |
| 修稿时间： | 2006-09-26 |
Magnetic Behaviour and Heating Effect of Fe3O4 Ferrofluids Composed of Monodisperse Nanoparticles |
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| ZHANG Li-Ying,DOU Yong-Hua,ZHANG Ling,GU Hong-Chen.Magnetic Behaviour and Heating Effect of Fe3O4 Ferrofluids Composed of Monodisperse Nanoparticles[J].Chinese Physics Letters,2007,24(2):483-486. |
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| Authors: | ZHANG Li-Ying DOU Yong-Hua ZHANG Ling GU Hong-Chen |
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| Affiliation: | National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Films and Microfabrication of MOE, Research Institute of Micro and Nano Science and Technology, Shanghai diaotong University, Shanghai 200030 |
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| Abstract: | Fe3O4 ferrofluids containing monodisperse Fe3O4 nanoparticles with different diameters of 8, 12, 16 and 18nm are prepared by using high-temperature solution phase reaction. The particles have single crystal structures with arrow size distributions. At room temperature, the 8-nm ferrofluid shows perparamagnetic behaviour, whereas the others display hysteresis properties and the coercivity increases with the increasing particle size. The spin glass-like behaviour and cusps near 190K are observed on all ferrofluids according to the temperature variation of field-cooled (FC) and zero-field-cooled (ZFC) magnetization measurements. The cusps are found to be associated with the freezing point of the solvent. As a comparison, the ferrofluids are dried and the FC and ZFC magnetization curves of powdery samples are also nvestigated. It is found that the blocking temperatures for the powdery samples are higher than those for their corresponding ferrofluids. Moreover, the size dependent heating effect of the ferrofluids is also investigated in ac magnetic field with a frequency of 55kHz and amplitude of 200Oe. |
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| Keywords: | 47 65 Cb 75 50 +a 87 83 +a |
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