頁籤選單縮合
題名 | Role of Néel and Brownian Relaxation Mechanisms for Water-Based Fe₃O₄ Nanoparticle Ferrofluids in Hyperthermia |
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作者 | Zhang, Xuefeng; Chen, Shihwei; Wang, Huay-min; Hsieh, Shu-ling; Wu, Chun-hsin; Chou, Hsuan-hung; Hsieh, Shuchen; | 書刊名 | Biomedical Engineering: Applications, Basis and Communications |
卷期 | 22:5 2010.10[民99.10] |
頁次 | 頁393-399 |
分類號 | 410.1644 |
關鍵詞 | Fe₃O₄ nanoparticles; Hyperthermia; Néel relaxation; Brownian relaxation; |
語文 | 英文(English) |
英文摘要 | Abstract: Hydrophilic Fe3O4 nanoparticles with a mean diameter size of 15 nm were synthesized by means of the direct reduction of FeCl3 and FeCl2 in an aqueous solution. The heating properties of Fe3O4 nanoparticles under an alternating magnetic field were investigated in a frequency range of 50–500 kHz and a magnitude range of 3.1–5.0 kA/m. To distinguish the roles of Néel and Brownian relaxation mechanisms, polydimethylsiloxane (PDMS) and water were employed as a medium, in which PDMS plays a significant role of eliminating the effect of Brownian relaxation. It is experimentally and theoretically confirmed that, for the Fe3O4/water system, high-specific absorption rates are due to a combination of both mechanisms, with an enhanced contribution due to Néel relaxation with increasing frequency and magnitude of the alternating electromagnetic field. The contribution efficiency of Néel relaxation increases from 36–56% by increasing the electromagnetic field frequency from 50–300 kHz, and then retains a saturated value of ~ 56% at 300–500 kHz. Moreover, a linear increase of the contribution efficiency of Néel relaxation at 300 kHz was observed from 55–65% by increasing the magnitude of electromagnetic field at 3.1–5.0 kA/m. The current research can be widely-expanded to explain the electromagnetic heating effect of other ferrofluid systems. |
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