scholarly journals Импульсное перемагничивание антиферромагнитных наночастиц ферригидрита

2018 ◽  
Vol 60 (10) ◽  
pp. 1931
Author(s):  
Д.А. Балаев ◽  
А.А. Красиков ◽  
Д.А. Великанов ◽  
С.И. Попков ◽  
Н.В. Дубынин ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Magnetic Hysteresis ◽  
Pulse Length ◽  
Hysteresis Loops ◽  
Relaxation Effects ◽  
Antiferromagnetic Ordering ◽  
Dynamic Magnetization ◽  
Pulsed Fields ◽  
Maximum Field ◽  
Ferrimagnetic Nanoparticles

AbstractThe dynamic magnetization switching of ferrihydrite nanoparticles has been investigated by a pulsed magnetometer technique in maximum fields H _max of up to 130 kOe with pulse lengths of 4, 8, and 16 ms. Ferrihydrite exhibits antiferromagnetic ordering and defects cause the uncompensated magnetic moment in nanoparticles; therefore, the behavior typical of magnetic nanoparticles is observed. The dynamic hysteresis loops measured under the above-mentioned conditions show that the use of pulsed fields significantly broadens the temperature region of existence of the magnetic hysteresis and the coercivity can be governed by varying the maximum field and pulse length. This behavior is resulted from the relaxation effects typical of conventional ferro- and ferrimagnetic nanoparticles and the features typical of antiferromagnetic nanoparticles.

scholarly journals Recent Advances in Understanding Magnetic Nanoparticles in AC Magnetic Fields and Optimal Design for Targeted Hyperthermia

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Hiroaki Mamiya
Keyword(s):  
Magnetic Nanoparticles ◽  
Optimal Design ◽  
Magnetic Fields ◽  
Heat Dissipation ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Future Prospects ◽  
Hyperthermia Treatment ◽  
Selective Heating ◽  
Magnetic Hysteresis Loops

Targeted hyperthermia treatment using magnetic nanoparticles is a promising cancer therapy that enables selective heating of hidden microcancer tissues. In this review, I outline the present status of chemical synthesis of such magnetic nanoparticles. Then, the latest progress in understanding their heat dissipation mechanisms under large magnetic fields is overviewed. This review covers the recently predicted novel phenomena: magnetic hysteresis loops of superparamagnetic states and steady orientations of easy axes at the directions parallel, perpendicular, or oblique to the AC magnetic field. Finally, this review ends with future prospects from the viewpoint of optimal design for efficacy with a low side-effect profile.

scholarly journals Hydrothermal Novel Synthesis of Neck-structured Hyperthermia-suitable Magnetic (Fe3O4, γ-Fe2O3 and α-Fe2O3) Nanoparticles

2011 ◽  
Vol 4 (1) ◽  
pp. 99 ◽  
Author(s):  
M. S. Islam ◽  
J. Kurawaki ◽  
Y. Kusumoto ◽  
M. Abdulla-Al-Mamun ◽  
M. Z. Bin Mukhlish
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Magnetic Nanoparticles ◽  
Quantum Interference ◽  
Heat Dissipation ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Particle Morphology ◽  
Ferrous Chloride ◽  
Size And Morphology

Novel neck-structured Fe3O4, γ-Fe2O3 and α-Fe2O3 magnetic nanoparticles were successfully prepared by a modified hydrothermal method. Ferrous chloride tetrahydrate was solely used as a precursor for the novel nanomaterials. The X-ray diffractometric study revealed the purity of the nanomaterials thus synthesized. All of the products were characterized using a field-emission scanning electron microscope (FE-SEM) and a transmission electron microscope (TEM) for the particle size and morphology. Neck-structured particle morphology was observed for the first time in all of iron oxides with magnetic properties. The particle size observed was 50–60 nm. The synthesized nanomaterials showed excellent magnetization values when magnetic hysteresis loops were measured using a superconducting quantum interference device (SQUID). Moreover, the as-prepared magnetic nanoparticles suspensions showed significant temperature increments under an AC (alternating current) magnetic-field induction condition at room temperature which indicates the hyperthermia feasibility. Keywords: Magnetic materials; Neck-structured; Hyperthermia; Heat dissipation. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i1.8727J. Sci. Res. 4 (1), 99-107 (2012)

Preparation and physical characterization of cobalt iron oxide magnetic nanoparticles loaded polyvinyl alcohol

2021 ◽  
pp. 089270572098557
Author(s):  
M Abu-Abdeen ◽  
O Saber ◽  
E Mousa
Keyword(s):  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Polyvinyl Alcohol ◽  
Saturation Magnetization ◽  
Polymer Films ◽  
Magnetic Hysteresis ◽  
Thermal Method ◽  
Cobalt Iron Oxide ◽  
Cobalt Iron ◽  
Iron Oxide Magnetic Nanoparticles

A solvent thermal method which depends on a thermal process under critical temperature and pressure was used to prepare cobalt iron oxide magnetic nanoparticles with a molar ratio 2. The prepared particles were in the form of nanoparticles with diameter ranging from 5 to 10 nm and with amorphous structure. Magnetic hysteresis behavior with saturation magnetization 36.31 emu/g and coercivity 4 Oe were observed for the nanoparticles. Polyvinyl alcohol was loaded with different concentrations of cobalt iron oxide nanoparticles using casting technique. Hysteresis loops for the polymer films were observed and both the saturation magnetization and coercivity were increased from 0.36 to 16.03 emu/g and 115 to 293 Oe for samples containing 5 and 20 wt% of nanoparticles, respectively. The elastic modulus of films was increased from 2.7 to 4.9 GPa for unloaded and loaded samples with 20 wt%, respectively. The storage modulus of the polymer films was found to obey the percolation behavior.

Investigation on the Origin of Magnetization in Plastically Deformed NI51TI49 Alloy

2017 ◽  
Vol 743 ◽  
pp. 13-18
Author(s):  
Anna Drozdova ◽  
Alexander Nyavro ◽  
Lyudmila Kveglis
Keyword(s):  
Crystal Lattice ◽  
Magnetic Moments ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Lattice Curvature ◽  
Electron States ◽  
Large Atom ◽  
Transmission Electron ◽  
Large Distortion ◽  
Density Of Electron States

The article deals with the investigation of structure and magnetic properties of plastically deformed Ni51Ti49 alloy. The magnetic hysteresis loops confirm the presence of ferromagnetic properties in the alloy. The transmission electron microscopy (TEM) detects the appearance of lenticular crystals with bending contours which indicate the large distortion of the crystal lattice. The crystal lattice curvature occurs due to the large atom displacement. As a result, icosahedral clusters with the Frank-Kasper (FK) structure can be formed. The spin-polarized density of electron states and the magnetic moments for both non-deformed (near-spherical structure) and deformed (elongated by 5% along the Z-axis) Ni7Ti5 (FK-12), Ni8Ti5 (FK-13), and Ni10Ti6 (FK-16) clusters are calculated for the explanation of possibility of magnetization appearance in Ni51Ti49 alloy. The calculations show the increase in the magnetic moments for the deformed clusters. The calculated spectra demonstrate the high density of electron states near the Fermi level which is a characteristic feature of ferromagnetic alloys.

Simulations of magnetic hysteresis loops at high temperatures

2014 ◽  
Vol 116 (12) ◽  
pp. 123910 ◽  
Author(s):  
M. L. Plumer ◽  
J. van Ek ◽  
J. P. Whitehead ◽  
T. J. Fal ◽  
J. I. Mercer
Keyword(s):  
High Temperatures ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loops

scholarly journals Developing a reference material set for the magnetic properties of NdFeB alloy-based hard magnetic materials

2019 ◽  
Vol 15 (1) ◽  
pp. 21-27
Author(s):  
E. A. Volegova ◽  
T. I. Maslova ◽  
V. O. Vas’kovskiy ◽  
A. S. Volegov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetic Loss ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Hysteresis Loop ◽  
Magnetic Characteristics ◽  
Hard Magnetic Materials ◽  
Certified Values

Introduction The introduction indicates the need for the use of permanent magnets in various technology fields. The necessity of measuring the limit magnetic hysteresis loop for the correct calculation of magnetic system parameters is considered. The main sources of error when measuring boundary hysteresis loops are given. The practical impossibility of verifying blocks of magnetic measuring systems element-by-element is noted. This paper is devoted to the development of reference materials (RMs) for the magnetic properties of hard magnetic materials based on Nd2Fe14B, a highly anisotropic intermetallic compound.Materials and measuring methods Nd-Fe-B permanent magnets were selected as the material for developing the RMs. RM certified values were established using a CYCLE‑3 apparatus included in the GET 198‑2017 State Primary Measurement Standard for units of magnetic loss power, magnetic induction of constant magnetic field in a range from 0.1 to 2.5 T and magnetic flux in a range from 1·10–5 to 3·10–2 Wb.Results and its discussion Based on the experimentally obtained boundary hysteresis loops, the magnetic characteristics were evaluated, the interval of permitted certified values was set, the measurement result uncertainty of certified values was estimated, the RM validity period was established and the first RM batch was released.Conclusion On the basis of conducted studies, the RM type for magnetic properties of NdFeB alloy-based hard magnetic materials was approved (MS NdFeB set). The developed RM set was registered under the numbers GSO 11059–2018 / GSO 11062–2018 in the State RM Register of the Russian Federation.

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