Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires

AbstractThe induced thermal stress in a heating process is an important parameter to be known and controlled in the magnetization process of core-shell nanowires. This paper analyses the stress produced by a laser heating source placed at one end of a core-shell type structure. The thermal field was computed with the non-Fourier heat transport equation using a finite element method (FEM) implemented in Comsol Multiphysics. The internal stresses are essentially due to thermal gradients and different expansion characteristics of core and shell materials. The stress values were computed using the thermo elastic formalism and are depending on the laser beam parameters (spot size, power etc.) and system characteristics (dimensions, thermal characteristics). Stresses in the GPa range were estimated and consequently we find that the magnetic state of the system can be influenced significantly. A shell material as the glass which is a good thermal insulator induces in the magnetic core, the smaller stresses and consequently the smaller magnetoelastic energy. These results lead to a better understanding of the switching process in the magnetic materials.

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Magnetic properties of GaAs-Fe3Si core-shell nanowires—A comparison of ensemble and single nanowire investigation

AIP Advances ◽

10.1063/1.4973748 ◽

2017 ◽

Vol 7 (5) ◽

pp. 056305

Author(s):

Maria Hilse ◽

Bernd Jenichen ◽

Jens Herfort

Keyword(s):

Magnetic Properties ◽

Core Shell ◽

Single Nanowire ◽

Shell Nanowires

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Evaluation of iron-cobalt/ferrite core-shell nanoparticles for cancer thermotherapy

Journal of Applied Physics ◽

10.1063/1.2830975 ◽

2008 ◽

Vol 103 (7) ◽

pp. 07A307 ◽

Cited By ~ 173

Author(s):

A. H. Habib ◽

C. L. Ondeck ◽

P. Chaudhary ◽

M. R. Bockstaller ◽

M. E. McHenry

Keyword(s):

Cobalt Ferrite ◽

Core Shell ◽

Ferrite Core ◽

Shell Nanoparticles ◽

Iron Cobalt ◽

Core Shell Nanoparticles

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Preparation of Ferromagnetic Manganese Doped Cobalt Ferrite-Silica Core Shell Nanoparticles for Possible Biological Application

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.334-335.19 ◽

2013 ◽

Vol 334-335 ◽

pp. 19-25 ◽

Cited By ~ 1

Author(s):

S. Rostamzadehmansoor ◽

Mirabdullah Seyed Sadjadi ◽

K. Zare ◽

Nazanin Farhadyar

Keyword(s):

Magnetic Properties ◽

Room Temperature ◽

Cobalt Ferrite ◽

Biomedical Application ◽

Strong Dependence ◽

Precipitation Method ◽

Cell Protein ◽

Core Shell ◽

X Ray ◽

Cell Parameters

Magnetic oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection and cell/protein separations. In this work, we investigated synthesis, magnetic properties of silica coated metal ferrite, (CoFe2O4)/SiO2 and manganese doped cobalt ferrite nanoparticles (Mnx-Co1-xFe2O4 with x = 0.02, 0.04 and 0.06)/SiO2 for possible biomedical application. All the ferrites nanoparticles were prepared by co-precipitation method using FeCl3.6H2O, CoCl2.6H2O and MnCl2.2H2O as precursors, and were silica coated by the Stober process in directly ethanol. The composition, phase structure and morphology of the prepared core/shell cobalt ferrites nanostructures were characterized by powder X-ray diffraction (XRD), Fourier Transform infra-red spectra (FTIR), Field Emission Scanning Electron Microscopy and energy dispersive X-ray analysis (FESEM-EDAX). The results revealed that all the samples maintain the ferrite spinel structure. While, the cell parameters decrease monotonically by increase of Mn content indicating that the Mn ions are substituted into the lattice of CoFe2O4. The magnetic properties of the prepared samples were investigated at room temperature using Vibrating Sample Magnetometer (VSM). The results revealed a strong dependence of room temperature magnetic properties on (1) doping content, x; (2) particle size and ion distributions.

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Structural and magnetic properties of hybrid ferromagnetic metal/semiconductor (ZnTe)/Co core-shell nanowires

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2014.11.031 ◽

2015 ◽

Vol 412 ◽

pp. 80-86 ◽

Cited By ~ 2

Author(s):

P.A. Misiuna ◽

P. Dłużewski ◽

T. Wojciechowski ◽

E. Milińska ◽

B. Kurowska ◽

...

Keyword(s):

Magnetic Properties ◽

Ferromagnetic Metal ◽

Core Shell ◽

Structural And Magnetic Properties ◽

Shell Nanowires

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Magnetic core–shell nanowires as MRI contrast agents for cell tracking

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00597-3 ◽

2020 ◽

Vol 18 (1) ◽

Cited By ~ 4

Author(s):

Aldo Isaac Martínez-Banderas ◽

Antonio Aires ◽

Sandra Plaza-García ◽

Lorena Colás ◽

Julián A. Moreno ◽

...

Keyword(s):

Contrast Agents ◽

Cell Tracking ◽

Magnetic Core ◽

Mri Contrast Agents ◽

Core Shell ◽

Mri Contrast ◽

Shell Nanowires

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Engineering Core-Shell Structures of Magnetic Ferrite Nanoparticles for High Hyperthermia Performance

Nanomaterials ◽

10.3390/nano10050991 ◽

2020 ◽

Vol 10 (5) ◽

pp. 991 ◽

Cited By ~ 2

Author(s):

Mohamed S. A. Darwish ◽

Hohyeon Kim ◽

Hwangjae Lee ◽

Chiseon Ryu ◽

Jae Young Lee ◽

...

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Cobalt Ferrite ◽

Magnetic Core ◽

Ferrite Nanoparticles ◽

Shell Structures ◽

Precipitation Process ◽

Core Shell ◽

Heating Efficiency

Magnetic ferrite nanoparticles (MFNs) with high heating efficiency are highly desirable for hyperthermia applications. As conventional MFNs usually show low heating efficiency with a lower specific loss power (SLP), extensive efforts to enhance the SLP of MFNs have been made by varying the particle compositions, sizes, and structures. In this study, we attempted to increase the SLP values by creating core-shell structures of MFNs. Accordingly, first we synthesized three different types of core ferrite nanoparticle of magnetite (mag), cobalt ferrite (cf) and zinc cobalt ferrite (zcf). Secondly, we synthesized eight bi-magnetic core-shell structured MFNs; Fe3O4@CoFe2O4 (mag@cf1, mag@cf2), CoFe2O4@Fe3O4 (cf@mag1, cf@mag2), Fe3O4@ZnCoFe2O4 (mag@zcf1, mag@zcf2), and ZnCoFe2O4@Fe3O4 (zcf@mag1, zcf@mag2), using a modified controlled co-precipitation process. SLP values of the prepared core-shell MFNs were investigated with respect to their compositions and core/shell dimensions while varying the applied magnetic field strength. Hyperthermia properties of the prepared core-shell MFNs were further compared to commercial magnetic nanoparticles under the safe limits of magnetic field parameters (<5 × 109 A/(m·s)). As a result, the highest SLP value (379.2 W/gmetal) was obtained for mag@zcf1, with a magnetic field strength of 50 kA/m and frequency of 97 kHz. On the other hand, the lowest SLP value (1.7 W/gmetal) was obtained for cf@mag1, with a magnetic field strength of 40 kA/m and frequency of 97 kHz. We also found that magnetic properties and thickness of the shell play critical roles in heating efficiency and hyperthermia performance. In conclusion, we successfully enhanced the SLP of MFNs by engineering their compositions and dimensions.

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