Study of Magnetic Properties and Relaxation Time of Nanoparticle Fe3O4-SiO2

Abstract

The magnetic properties and relaxation time of Fe3O4 nanoparticles, and their encapsulation with silicon dioxide (Fe3O4-SiO2), have been successfully investigated by analyzing the temperature dependence of magnetization (()) and the time dependence of magnetization (()), using the SQUID magnetometer measurement. The () measurement results can determine the magnetic parameters and magnetic irreversibility of Fe3O4 and Fe3O4-SiO2 samples. The values of Curie constant (), effective magnetic moment (), and Weiss temperature () are 4.2 (emu.K.Oe/mol), 5.77 , and −349 K, respectively, for the Fe3O4 samples, and 81.3 (emu.K.Oe/mol), 25.49 , and −2440 K, respectively, for the Fe3O4-SiO2 samples. After encapsulation, the broadening peak deviation decreased from 281.6 K to 279 K, indicating that the superparamagnetic interactions increased with the encapsulation process. The magnetic parameters and irreversibility values showed that the superparamagnetic properties increased significantly after encapsulation (Fe3O4-SiO2). From the results of the () measurement, it was found that there was a decrease in the magnetic relaxation time after the encapsulation process, which indicated that the distribution of the nanoparticle size and anisotropy energy increased.

Design Principles of Responsive Relaxometric 19F Contrast Agents: Evaluation from the Point of View of Relaxation Theory and Experimental Data

“…The effective magnetic moment (μ eff ) can be calculated based on eq . However, such approximation is not generally valid because strong ligand field effects exist. ,,, Effective magnetic moments are usually determined experimentally using the Evans method or SQUID magnetometry for a given compound. Most authors use tabularized data (Table ) obtained from the measurements of various macrocyclic complexes of paramagnetic ions.…”

Economic and Accessible Portable Homemade Magnetic Hyperthermia System: Influence of the Shape, Characteristics and Type of Nanoparticles in Its Effectiveness

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