Crystallographic and magnetic properties of the hyperthermia material CoFe₂O₄@AlFe₂O₄

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• 作者：Hyunkyung Choi ; Mijeong An ; Wonyoung Eom…
• 关键词：Hyperthermia ; Nanoparticles ; Core/shell structure ; Mössbauer spectroscopy
• 刊名：Journal of the Korean Physical Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：70
• 期：2
• 页码：173-176
• 全文大小：
• 刊物主题：Physics, general; Theoretical, Mathematical and Computational Physics; Particle and Nuclear Physics;
• 出版者：The Korean Physical Society
• ISSN：1976-8524
• 卷排序：70

文摘

Hard/soft CoFe₂O₄@AlFe₂O₄ core/shell nanoparticles were prepared by using a high temperature thermal decomposition method with seed-mediated growth. The structural, magnetic and thermal properties of the nanoparticles were investigated by using X-ray diffraction, vibrating sample magnetometer, MagneTherm, and Mössbauer spectroscopy. The crystal structure of nanoparticles was determined to be cubic spinel ferrite with space group Fd-3m. The CoFe₂O₄ nanoparticles were found to show high magnetization and coercivity while AlFe₂O₄ nanoparticles were found to show low magnetization and coercivity. The CoFe₂O₄@AlFe₂O₄ core/shell nanoparticles showed intermediate values of magnetization and the coercivity between those of CoFe₂O₄ and AlFe₂O₄. Also, the blocking temperature (T_B) of the nanoparticles (NPs) was observed to be 280, 50, and 225 K for CoFe₂O₄, AlFe₂O₄ and CoFe₂O₄@AlFe₂O₄, respectively. The core/shell ferrite shows a T_B near 225 K, associated with the harder CoFe₂O₄ NPs. Temperatures below 225 K, the zero-field-cooled curves show changes in their slopes at a temperature near 50 K, corresponding to the second blocking temperature associated with the softer AlFe₂O₄ NPs.