Shape control and associated magnetic and dielectric properties of MFe12O19 (M = Ba, Pb, Sr) hexaferrites

Amini, Mahboobeh; Gholizadeh, Ahmad

doi:10.1016/j.jpcs.2020.109660

Cited by 65 publications

(25 citation statements)

References 52 publications

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“…As a result, it can be said that a higher amount of relaxation time indicates the higher mobility of charge carriers. 61,68,69 Therefore, with the increase of the Ca and Gd co-substitution contents for x up to 0.12, the conduction process is mainly governed by the long-range movement of the electrical charge carriers based on the Debye dielectric response, which can be attributed to the decrease in grain resistance in accordance to our AC conductivity results.…”

Section: Dielectric Propertiessupporting

confidence: 83%

“…The value of the n between 0 and 1 indicates that the electron hopping attributed to the short translational motion is assisted by a small polaronic mechanism, whereas the n greater than 1 shows that localized or reorientation hopping assisted by a large polaronic mechanism takes place between adjacent cites. 61,66,67 The values of the n in our samples are lower than 1, which emphasizes the electron hopping attributed to the short translational motion. The conductivity of the prepared samples decreases with increasing the Ca-Gd content up to x = 0.12 due to larger grain size, which in turn the less charge scattering takes place by defects and grain boundaries leading to the long-range movement of the electrical charge carriers based on the Debye dielectric response.…”

Section: Dielectric Propertiesmentioning

confidence: 58%

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Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

Gholizadeh

Banihashemi

2023

J Am Ceram Soc.

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Sr 1−x Ca x Fe 12−x Gd x O 19 (x = 0, 0.04, 0.08, 0.12, 0.16, 0.20) hexaferrites were characterized by several techniques, such as X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, and vibrating sample magnetometer. Structural results indicate the formation of a pure-phase Sr 1−x Ca x Fe 12−x Gd x O 19 hexaferrite with space group P6 3 /mmc. SEM photography confirms that there are a smaller number of defects due to the reduced porosity and surface area (increased particle size). Magnetic investigations showed a rise of the coercive force from 5069.8 to 5757.4 Oe and saturation magnetization from 79.25 to 80.68 emu/g. The maximum values appear to be for sample x = 0.16, which may be useful in such as permanent magnets, and high-density media for magnetic storage devices. Dielectric parameters, such as conductivity, the real part of permittivity, dielectric loss, dielectric tangent loss, and complex modulus, were studied. Impedance analysis shows that the conduction process is mainly governed by the long-range movement of the charge carriers based on the Debye model for x = 0.12.

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Section: Dielectric Propertiessupporting

confidence: 83%

Section: Dielectric Propertiesmentioning

confidence: 58%

Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

Gholizadeh

Banihashemi

2023

J Am Ceram Soc.

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“…But, the further increase in the frequency causes to change the direction of the electron's motion before reaching the boundaries, resulting in fewer electrons reaching the grain boundary. Hence, the weaker bilayer structure and lower interfacial polarization are created which results in a decrease of dielectric constant (Amini and Gholizadeh, 2020). As shown in Figures 10A,B, the maximum value for the dielectric constant (real and imaginary part) are observed in sample x 0.20 and the lowest value in sample x 0.00.…”

Section: Dielectric Propertiesmentioning

confidence: 93%

“…The higher the amount of energy consumed for electron exchange, the greater the energy loss. On the other hand, due to the obvious role of the grain in the electron exchange and the lower resistivity of the grains at higher frequencies, the amount of energy required for electron transfer is reduced and consequently the amount of dielectric loss is reduced (Amini and Gholizadeh, 2020;Beyranvand and Gholizadeh, 2020;Gholizadeh and Beyranvand, 2020). The strong dispersion in the low frequency region and the high value of the measured dielectric constant of sample x 0.20 being large is due to the combined influence of space charge effects arising from species like Fe 2+ ions, oxygen vacancies, and grain boundary defects.…”

Section: Dielectric Propertiesmentioning

confidence: 99%

Cadmium Substitution Effect on Microstructure and Magnetic Properties of Mg-Cu-Zn Ferrites

2022

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The microstructure, optical, and magnetic properties of CdxMg0.3-xCu0.2Zn0.5Fe2O4 ferrites prepared by the citrate auto-combustion method were investigated. The samples were analyzed by X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, https://soh.iums.ac.ir/uploads/uv-vis_-_2.pptx X-ray energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometer. Rietveld refinement of XRD patterns shows a single-phase cubic structure (space group Fd3¯m) for the samples with x up to 0.20, while the impurity phase of CdO is observed in the samples with x = 0.25, 0.30. As the substitution content increases, the presence of non-magnetic Cd2+ ions in the octahedral site and the migration of Fe3+ions from the octahedral site to the tetrahedral site decreases the saturation magnetization of the samples. Comparison of the bandgap energy of the samples shows an increasing trend with Cd substitution for x up to 0.20 and then decreases, which can be interpreted in terms of changes in the electronic structure of the samples. Improvement in dielectric properties of the samples with increase of Cd2+ content for x up to 0.20 may be attributed to easier transfer and electron exchange between Fe3+and M2+ ions.

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“…[51] However, based on their crystal structures, ferrites can be divided into four, i.e., spinel, garnet, ortho, and hexagonal ferrites. [52][53][54][55] Unlike spinel and garnet ferrites, hexagonal ferrites are anisotropic and have a greater inherent magnetocrystalline anisotropy field. Due to their in-plane anisotropy, hexaferrite has a natural resonance in the GHz region, making them suitable as high-frequency absorbers.…”

Section: Hexagonal Ferritesmentioning

confidence: 99%

Recent Progress in Hexagonal Ferrites Based Composites for Microwave Absorption

Mohammed

Mohammed²,

Srivastava

2022

Cryst. Res. Technol.

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With the fast growth of wireless communication technology in high‐frequency ranges, electromagnetic (EM) interference has become a growing concern that has drawn international attention. The development of materials that can absorb EM radiation is a crucial solution. This review provides a detailed overview of ferrites, specifically hexagonal ferrites and their composites for microwave (MW) absorption. It examines hexagonal ferrite classifications based on the stacking order of their fundamental blocks and their synthesis methods and strategies for improving their magnetic properties. On the other hand, this review included a detailed examination of hexagonal ferrites–conducting polymer, hexagonal ferrites–2D materials, and hexagonal ferrite–other nanomaterials composites for MW absorption applications. Enhancing MW absorption in hexagonal ferrites‐based microwave absorption materials (MAMs) regulates their EM characteristics, improves impedance matching, and creates a diversity of loss mechanisms. In addition, the limitations, challenges, and opportunities of hexagonal ferrites‐based MAMs are discussed, which will be helpful to those working in related areas. As a general application potential, it is worth mentioning that, as a result of recent promising findings in the synthesis of hexagonal ferrites‐based composites, hexaferrite‐based composites are suitable devices in the area of microwave absorption.

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Shape control and associated magnetic and dielectric properties of MFe12O19 (M = Ba, Pb, Sr) hexaferrites

Cited by 65 publications

References 52 publications

Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

Cadmium Substitution Effect on Microstructure and Magnetic Properties of Mg-Cu-Zn Ferrites

Recent Progress in Hexagonal Ferrites Based Composites for Microwave Absorption

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