Effect of hydrogenation on the structure and magnetic properties of an iron oxide cluster

AbstractWe report on high transversal relaxivity values of composite iron oxide-silica nanoparticles. To obtain the material, pre-formed maghemite nanoparticles were coated with silica by sol-gel chemistry, using supercritical fluids as the reaction media. The composite particles were monodisperse and consisted of a core of several maghemite nanoparticles, surrounded by a thick silica shell. The high pressure and high temperature process did not affect the iron oxide particle size but induced an increase on their saturation magnetization values, possibly due to an improvement of the particle crystallinity. These iron oxide-based materials present very high transversal relaxivity values which can be correlated to the magnetic moment and to the silica shell width of the composite particles. Moreover, composite particles are not cytotoxic and they are dispersable in polar solvents.

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Ultrasmall Iron Oxide Particle Contrast Agent and MRI Can Be Used to Monitor the Effect of Anti-Rejection Treatment

Transplantation Journal ◽

10.1097/01.tp.0000276957.62313.fe ◽

2007 ◽

Vol 84 (3) ◽

pp. 374-379 ◽

Cited By ~ 6

Author(s):

Eva Penno ◽

Lars Johansson ◽

H??kan Ahlstr??m ◽

Cecilia Johnsson

Keyword(s):

Iron Oxide ◽

Contrast Agent ◽

Oxide Particle ◽

Iron Oxide Particle

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Synthesis of transparent magnetic particle/organic hybrid film using iron–organics

Journal of Materials Research ◽

10.1557/jmr.2000.0304 ◽

2000 ◽

Vol 15 (10) ◽

pp. 2114-2120 ◽

Cited By ~ 18

Author(s):

Toshinobu Yogo ◽

Tomoyuki Nakamura ◽

Wataru Sakamoto ◽

Shin-ichi Hirano

Keyword(s):

Iron Oxide ◽

Magnetization Curve ◽

Magnetic Particles ◽

Magnetic Particle ◽

Hybrid Film ◽

Oxide Particle ◽

Iron Oxide Particle ◽

Organic Hybrid ◽

Hydrolysis Conditions

A transparent magnetic particle/organic film was synthesized from an iron–organic compound. Iron(III) 3-allylacetylacetonate (IAA) was polymerized followed by in situ hydrolysis yielding an iron oxide particle/oligomer hybrid. The sizes of magnetic particles were dependent upon the hydrolysis conditions of the IAA oligomers. A nanometer-sized ferrimagnetic iron oxide particle/oligomer hybrid showed a magnetization curve with no coercive force at 300 K and that with Hc of 200 Oe at 4.2 K, respectively. The magnetization versus H/T curves at 300 and 77 K were superimposed on each other and satisfied the Langevin equation. The transparent hybrid film showed a magnetization curve at room temperature. The absorption spectrum of the film was shifted to higher energy by 0.14 eV compared with that of bulk magnetite. The absorption edge of the film was blue-shifted.

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Influence of Co and Mn substitution on magnetic properties of novel Y2FeSi Heusler alloy

Modern Physics Letters B ◽

10.1142/s0217984921500883 ◽

2021 ◽

Vol 35 (05) ◽

pp. 2150088

Author(s):

G. Kasprzak ◽

J. Rzacki

Keyword(s):

Magnetic Properties ◽

Spin Polarization ◽

Magnetic Moment ◽

Density Functional ◽

Magnetic Moments ◽

Heusler Alloys ◽

Total Magnetic Moment ◽

Functional Theory ◽

Structure Changes ◽

Mn Substitution

This paper presents results of density functional theory (DFT) studies on structural, electronic, and magnetic properties of novel Y2FeSi Heusler material characterized by spin polarization at Fermi level of [Formula: see text] and magnetic moment of 1.56 [Formula: see text]. The total magnetic moment of investigated material is dominated by Iron sites, while magnetic moments coming from Yttrium sites are aligned antiparallel to the Iron. Here, we introduced Co and Mn substitutions to alter the magnetic and electronic properties of the studied material. The Heusler alloys are very sensitive to electronic structure changes induced by ionic substitutions, which allowing to specifically modulate their properties. The Co-substitution lowered the total magnetic moment to [Formula: see text][Formula: see text]1.20 [Formula: see text] and Mn caused a rise to [Formula: see text][Formula: see text]1.93 [Formula: see text]. Introduction of Mn resulted in [Formula: see text] spin polarization. We hope that this study will promote further theoretical as well as experimental interest in these types of compounds.

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Magnetically modified bentonite as a possible contrast agent in MRI of gastrointestinal tract

Chemical Papers ◽

10.2478/s11696-007-0057-9 ◽

2007 ◽

Vol 61 (5) ◽

Cited By ~ 14

Author(s):

H. Bartonkova ◽

M. Mashlan ◽

I. Medrik ◽

D. Jancik ◽

R. Zboril

Keyword(s):

Mössbauer Spectroscopy ◽

Iron Oxide ◽

Contrast Agent ◽

Mossbauer Spectroscopy ◽

Oxide Particle ◽

Negative Contrast ◽

Iron Oxide Particle ◽

Hyperfine Parameters ◽

Mößbauer Spectroscopy ◽

Negative Contrast Agent

AbstractA composite of iron oxide nanoparticles and mineral matrix has been studied by XRD, Mössbauer spectroscopy, and TEM. Magnetite and superparamagnetic magnetite have been identified by Mössbauer spectroscopy in the nanocomposite. A relationship between the hyperfine parameters and iron oxide particle size has been confirmed by TEM. The optimal concentration of “magnetite—bentonite” composite, when the MRI signal is fully reduced, was found for using this composite as a negative contrast agent.

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