scholarly journals Thermal Traits of MNPs under High-Frequency Magnetic Fields: Disentangling the Effect of Size and Coating

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 797
Author(s):  
David Aurélio ◽  
Jiří Mikšátko ◽  
Miroslav Veverka ◽  
Magdalena Michlová ◽  
Martin Kalbáč ◽  
...  
Keyword(s):  
Oleic Acid ◽  
High Frequency ◽  
Cobalt Ferrite ◽  
Specific Power ◽  
Undecanoic Acid ◽  
Temperature Dependent ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
Ethanol System ◽  
The Impact

We investigated the heating abilities of magnetic nanoparticles (MNPs) in a high-frequency magnetic field (MF) as a function of surface coating and size. The cobalt ferrite MNPs were obtained by a hydrothermal method in a water–oleic acid–ethanol system, yielding MNPs with mean diameter of about 5 nm, functionalized with the oleic acid. By applying another cycle of hydrothermal synthesis, we obtained MNPs with about one nm larger diameter. In the next step, the oleic acid was exchanged for 11-maleimidoundecanoic acid or 11-(furfurylureido)undecanoic acid. For the heating experiments, all samples were dispersed in the same solvent (dichloroethane) in the same concentration and the heating performance was studied in a broad interval of MF frequencies (346–782 kHz). The obtained results enabled us to disentangle the impact of the hydrodynamic, structural, and magnetic parameters on the overall heating capabilities. We also demonstrated that the specific power absorption does not show a monotonous trend within the series in the investigated interval of temperatures, pointing to temperature-dependent competition of the Brownian and Néel contributions in heat release.

Motion behavior of non-metallic particles under high frequency magnetic field

2009 ◽  
Vol 19 (3) ◽  
pp. 674-680 ◽  
Author(s):  
Zhong-tao ZHANG ◽  
Qing-tao GUO ◽  
Feng-yun YU ◽  
Jie LI ◽  
Jian ZHANG ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Metallic Particles ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
Motion Behavior

High frequency magnetic field sensors based on the Faraday effect in garnet thick films

1992 ◽  
Vol 60 (17) ◽  
pp. 2048-2050 ◽  
Author(s):  
R. Wolfe ◽  
E. M. Gyorgy ◽  
R. A. Lieberman ◽  
V. J. Fratello ◽  
S. J. Licht ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Faraday Effect ◽  
Thick Films ◽  
Magnetic Field Sensors ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field

scholarly journals ANALYSIS OF HIGH-FREQUENCY C-CORE MAGNETIC FLUX LEAKAGES FOR BONE TUMOR WITH INDUCTION HEATING BY USING MULTI-COIL

2019 ◽  
Author(s):  
Metharak Jokpudsa ◽  
Supawat Kotchapradit ◽  
Chanchai Thongsopa ◽  
Thanaset Thosdeekoraphat
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Tumor Tissue ◽  
Low Frequency ◽  
Heat Energy ◽  
High Frequencies ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
The Magnetic Field ◽  
Flux Leakage

High-frequency magnetic field has been developed pervasively. The induction of heat from the magnetic field can help to treat tumor tissue to a certain extent. Normally, treatment by the low-frequency magnetic field needed to be combined with magnetic substances. To assist in the induction of magnetic fields and reduce flux leakage. However, there are studies that have found that high frequencies can cause heat to tumor tissue. In this paper present, a new magnetic application will focus on the analysis of the high-frequency magnetic nickel core with multi-coil. In order to focus the heat energy using a high-frequency magnetic field into the tumor tissue. The magnetic coil was excited by 915 MHz signal and the combination of tissues used are muscle, bone, and tumor. The magnetic power on the heating predicted by the analytical model, the power loss density (2.98e-6 w/m3) was analyzed using the CST microwave studio.

scholarly journals Difference between Brownian and Néel relaxation mechanisms in a magnetizing field

2021 ◽  
pp. 14-20
Author(s):  
Alexander V. Lebedev ◽  
Keyword(s):  
Relaxation Time ◽  
Oleic Acid ◽  
High Frequency ◽  
Cobalt Ferrite ◽  
Magnetic Moments ◽  
Relaxation Mechanism ◽  
Dynamic Susceptibility ◽  
Magnetite Particles ◽  
Magnetizing Field ◽  
Néel Relaxation

Measurements of the dynamic susceptibility of a magnetic fluid based on cobalt ferrite particles stabilized in water by a double surfactant layer have been carried out. Cobalt ferrite, in comparison with magnetite, has a significantly higher energy of magnetic anisotropy. Therefore, for particles of cobalt ferrite, the Brownian mechanism of relaxation of magnetic moments is characteristic. The Debye (with a finite relaxation time) contribution to the dynamic susceptibility and the high-frequency (dispersionless) contribution are distinguished by constructing Cole-Cole diagrams. It was found that with an increase in the magnetizing field, the Debye contribution to the dynamic susceptibility decreases, while the high-frequency one (having a zero relaxation time) remains unchanged. The indicated property of the dynamic susceptibility of a fluid with a Brownian relaxation mechanism is radically different from the properties of the susceptibility of a fluid with Néel particles. Previously, measurements were made of the susceptibility of a fluid based on magnetite particles stabilized with oleic acid in kerosene. The magnetite particles have significantly lower anisotropy energy and are characterized by the predominance of the Néel relaxation mechanism. Turning on the magnetizing field caused a decrease in both the Debye part of the susceptibility and the high-frequency part of the susceptibility of magnetite particles.

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