Functional Properties and Microstructure Development of Micro-Nano Fe/MgO Composite

The influence of size and doping effects on the magnetization M, phonon ω and band gap energy Eg of MgO nanoparticles is studied using a microscopic model. The room-temperature ferromagnetism is due to surface or/and doping effects in MgO nanoparticles (NPs). The influence of the spin–phonon interaction is discussed. M increases with decreasing NP size. M and Eg can increase or decrease by different ion doping (Co, Al, La, Fe) due to the different strain that appears. It changes the lattice parameters and the exchange interaction constants. We found that MgO NP with size of 20 nm and Fe- or Co-doping concentration x = 0.1 and x = 0.2, respectively, have a Curie temperature TC = 315 K, i.e., they are appropriate for application in magnetic hyperthermia, they satisfy the conditions for that. The energy of the phonon mode ω = 448 cm−1 increases with decreasing NP size. It increases with increasing Co and Fe, or decreases with Sr ion doping.

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“…A maximum in the coercive field

is obtained as a function of the Fe and Co ion dopants (see Figure 5 ). Bures et al [ 53 ] also reported an increase of

in Fe-doped MgO NPs for

. Unfortunately, above this value there are no experimental data.…”

Section: Numerical Results and Discussionmentioning

confidence: 88%

Magnetic, Optical and Phonon Properties of Ion-Doped MgO Nanoparticles. Application for Magnetic Hyperthermia

2023

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“…With the increasing surface roughness of micron particles, it is necessary to use somewhat larger nanoparticles for perfect surface coverage, and at the same time the percolation threshold increases, as was shown in a previous study. 51…”

Section: ■ Discussionmentioning

confidence: 99%

Formation of Effective Non-ferromagnetic Barrier in Fe/MgO Soft Magnetic Composite

Bures,

Neslusan,

Faberova

et al. 2024

ACS Appl. Electron. Mater.

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Soft magnetic ferromagnetic/insulator composites are complex objects in terms of structure and magnetic properties. They depend on many different parameters, among which one of the main ones is the amount of insulator. In this work, the effect of MgO content on magnetization processes in Fe/MgO composites is studied in detail by using a wide combination of properties and structure analysis methods. Several series of samples with content steps up to 0.1 wt % were prepared using standard powder metallurgy operations such as dry mixing, cold pressing, and sintering. The study demonstrates that the evolution of Barkhausen noise with increasing MgO content is not systematic. The second phase acts as an effective barrier to magnetic interaction between neighboring Fe particles only after reaching a certain point, which was found to be about 0.9% wt. Some other properties (coercivity, permeability, elastic properties) also demonstrate nontrivial composition dependence. To reveal the causes of the observed phenomena, the structure of the composites was studied in detail, and it was shown that with an increase in the MgO content in the range of 0.8−1%, a change in the mechanisms of structure formation occurs, which, in turn, affects the properties. The presented results provide insights into developing advanced soft magnetic composites with an optimal combination of a ferromagnetic powder and an insulator.

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Low core loss and high DC bias performance of FeSiAl soft magnetic composites cores with hybrid insulating layers of MgO/SiO2

Li,

Zhang,

Zhao

et al. 2024

Ceramics International

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Functional Properties and Microstructure Development of Micro-Nano Fe/MgO Composite

Cited by 3 publications

References 9 publications

Magnetic, Optical and Phonon Properties of Ion-Doped MgO Nanoparticles. Application for Magnetic Hyperthermia

Magnetic, Optical and Phonon Properties of Ion-Doped MgO Nanoparticles. Application for Magnetic Hyperthermia

Formation of Effective Non-ferromagnetic Barrier in Fe/MgO Soft Magnetic Composite

Low core loss and high DC bias performance of FeSiAl soft magnetic composites cores with hybrid insulating layers of MgO/SiO2

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