Effect of Dipole Interactions on Blocking Temperature and Relaxation Dynamics of Superparamagnetic Iron-Oxide (Fe3O4) Nanoparticle Systems
Date
2023-01-04
Authors
Sadat, Md Ehsan
Bud'ko, Sergey L.
Ewing, Rodney C.
Xu, Hong
Pauletti, Giovanni M.
Mast, David B.
Shi, Donglu
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Iowa State University Digital Repository, Ames IA (United States)
Abstract
The effects of dipole interactions on magnetic nanoparticle magnetization and relaxation dynamics were investigated using five nanoparticle (NP) systems with different surfactants, carrier liquids, size distributions, inter-particle spacing, and NP confinement. Dipole interactions were found to play a crucial role in modifying the blocking temperature behavior of the superparamagnetic nanoparticles, where stronger interactions were found to increase the blocking temperatures. Consequently, the blocking temperature of a densely packed nanoparticle system with stronger dipolar interactions was found to be substantially higher than those of the discrete nanoparticle systems. The frequencies of the dominant relaxation mechanisms were determined by magnetic susceptibility measurements in the frequency range of 100 Hz–7 GHz. The loss mechanisms were identified in terms of Brownian relaxation (1 kHz–10 kHz) and gyromagnetic resonance of Fe3O4 (~1.12 GHz). It was observed that the microwave absorption of the Fe3O4 nanoparticles depend on the local environment surrounding the NPs, as well as the long-range dipole–dipole interactions. These significant findings will be profoundly important in magnetic hyperthermia medical therapeutics and energy applications.
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IS-J 10975
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article
Comments
This article is published as Sadat, Md Ehsan, Sergey L. Bud’ko, Rodney C. Ewing, Hong Xu, Giovanni M. Pauletti, David B. Mast, and Donglu Shi. "Effect of Dipole Interactions on Blocking Temperature and Relaxation Dynamics of Superparamagnetic Iron-Oxide (Fe3O4) Nanoparticle Systems." Materials 16, no. 2 (2023): 496.
DOI: 10.3390/ma16020496.
Copyright 2023 by the authors.
Posted with permission.
DOE Contract Number(s): AC02-07CH11358.