Hexagonal Ferrites: Synthesis, Structure and Properties

A special issue of Magnetochemistry (ISSN 2312-7481). This special issue belongs to the section "Magnetic Materials".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 8995

Special Issue Editor

School of Materials Sciences and Engineering, Anhui University, Hefei 230601, China
Interests: hexaferrites; spinel ferrites; garnet ferrites; amorphous nanocrystalline soft magnetic materials; high-entropy ceramics; microwave absorbing materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue has focused on original research articles and critical reviews on “hexagonal ferrites:synthesis, structure and properties". The main aim is to focus on related topics by publishing the current developments in hexagonal ferrites.

Hexaferrites have attracted considerable attention due to their wide applicability, such as in permanent magnets, magnetic recording, and RF and microwave applications. They are classified into six types namely, M, U, W, X, Y, and Z, according to different stacking sequences of the three basic blocks S, R, and T in the crystal structure. Currently, hexaferrites have been explored for more exotic applications. This is particularly true as electronic components for mobile and wireless communications at microwave/GHz frequencies, electromagnetic wave absorbers for EMC, RAM and stealth technologies, and as composite materials.

This Special Issue of Magnetochemistry  on “hexagonal ferrites:synthesis, structure and properties" will closely follow the research in this topic to highlight the recent achievements of hexagonal ferrites from leading groups around the world. Synthesis, structure and properties of hexagonal ferrites, and their applications are appreciated.

In particular, the topics of interest include but are not limited to:

  • M-type hexaferrites;
  • W-type hexaferrites;
  • Y-type hexaferrites;
  • Z-type hexaferrites;
  • X-type hexaferrites;
  • U-type hexaferrites;
  • other hexaferrites;
  • composites of hexagonal ferrites and other materials.

Dr. Yujie Yang
Guest Editor

Manuscript Submission Information

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Keywords

  • hexaferrites
  • magnetic properties
  • delectric properties
  • microwave properties
  • optical properties
  • structural properties
  • ion substitution
  • morphology

Published Papers (5 papers)

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Research

17 pages, 5381 KiB  
Article
Two-Step Calcination-Method-Derived Al-Substituted W-Type SrYb Hexaferrites: Their Microstructural, Spectral, and Magnetic Properties
Magnetochemistry 2022, 8(10), 118; https://doi.org/10.3390/magnetochemistry8100118 - 30 Sep 2022
Cited by 1 | Viewed by 1402
Abstract
W-type hexaferrites were discovered in the 1950s and are of interest for their potential applications. In this context, many researchers have conducted studies on the partial substitution of Fe sites in order to modify their electric and magnetic properties. In this study, W-type [...] Read more.
W-type hexaferrites were discovered in the 1950s and are of interest for their potential applications. In this context, many researchers have conducted studies on the partial substitution of Fe sites in order to modify their electric and magnetic properties. In this study, W-type SrYb hexaferrites using Al3+ as substitutes for Fe3+ sites with the nominal composition Sr0.85Yb0.15Zn1.5Co0.5AlxFe16−xO27 (0.00 ≤ x ≤ 1.25) were successfully synthesized via the two-step calcination method. The microstructures, spectral bands of characteristic functional groups, morphologies, and magnetic parameters of the prepared samples were characterized using XRD, FTIR, SEM, EDX, and VSM. The XRD results showed that, compared with the standard patterns for the W-type hexaferrite, the W-type SrYb hexaferrites with the Al content (x) of 0.00 ≤ x ≤ 1.25 were a single-W-type hexaferrite phase. SEM images showed the flakes and hexagonal grains of W-type hexaferrites with various Al content (x). The saturation magnetization (Ms) and magneton number (nB) decreased with Al content (x) from 0.00 to 1.25. The remanent magnetization (Mr) and coercivity (Hc) decreased with Al content (x) from 0.00 to 0.25. Additionally, when the Al content (x) ≥ 0.25, Mr and Hc increased with the increase in the Al content (x). The magnetic anisotropy field (Ha) and first anisotropy constant (K1) increased with the Al content (x) increasing from 0.00 to 1.25. Al-substituted W-type SrYb hexaferrites with soft magnetic behavior, high Ms, and lower Hc may be used as microwave-absorbing materials. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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13 pages, 3474 KiB  
Article
Investigation into the Structural, Spectral, Magnetic, and Electrical Properties of Cobalt-Substituted Strontium W-Type Hexaferrites
Magnetochemistry 2022, 8(8), 75; https://doi.org/10.3390/magnetochemistry8080075 - 22 Jul 2022
Cited by 5 | Viewed by 1577
Abstract
The solid-state reaction method is used to synthesize W-type Sr hexagonal ferrites Sr0.8Pr0.2(Zn1.0−xCox)2Fe16O27 (x = 0.00, 0.15, 0.30, 0.45, 0.60, 0.75). The results of XRD for the W-type hexagonal ferrites, [...] Read more.
The solid-state reaction method is used to synthesize W-type Sr hexagonal ferrites Sr0.8Pr0.2(Zn1.0−xCox)2Fe16O27 (x = 0.00, 0.15, 0.30, 0.45, 0.60, 0.75). The results of XRD for the W-type hexagonal ferrites, when Co content (x) is 0.00 ≤ x ≤ 0.75, exhibit that they are in the single W-type hexaferrite phase. As shown by morphological analysis, the particles are hexagonal-shaped platelets. The saturation magnetization (Ms) and magneton number (nB) increases with Co content (x) from 0.00 to 0.60. Ms and nB begins to decrease at Co content (x) ≥ 0.60. With increasing Co content (x) from 0.00 to 0.75, the magnetic anisotropy field (Ha), first anisotropy constant (K1), and coercivity (Hc) decrease gradually. The values of DC electrical resistivity for W-type hexagonal ferrites Sr0.8Pr0.2(Zn1.0−xCox)2Fe16O27 (0.00 ≤ x ≤ 0.75) are in the range of 20.854 × 107 Ω-cm and 22.755 × 107 Ω-cm. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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8 pages, 1972 KiB  
Article
Microstructure and Magnetic Properties of M-Type Sr0.1Ca0.4La0.5Fe12O19 Ferrites: The Impact of Different Precursors
Magnetochemistry 2022, 8(7), 68; https://doi.org/10.3390/magnetochemistry8070068 - 25 Jun 2022
Cited by 2 | Viewed by 1219
Abstract
M-type Sr0.1Ca0.4La0.5Fe12O19 powder specimens doped with different precursors RFe2O4(R = Co, Ni, Cu, Zn, and Mg) were prepared via a traditional solid-state reaction method. The structural and magnetic properties of [...] Read more.
M-type Sr0.1Ca0.4La0.5Fe12O19 powder specimens doped with different precursors RFe2O4(R = Co, Ni, Cu, Zn, and Mg) were prepared via a traditional solid-state reaction method. The structural and magnetic properties of the specimens were studied. Only nthe single magnetoplumbite phase was found in all the specimens with uniformly distributed particles. The specimen with Zn-type precursor has the highest saturation (Ms), while the specimen with Co-type precursor has the highest remanent magnetism (Mr), coercivity (Hc), and the best comprehensive magnetic properties. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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13 pages, 4954 KiB  
Article
Structure, Spectra, Morphology, and Magnetic Properties of Nb5+ Ion-Substituted Sr Hexaferrites
Magnetochemistry 2022, 8(5), 51; https://doi.org/10.3390/magnetochemistry8050051 - 06 May 2022
Cited by 10 | Viewed by 1802
Abstract
SrFe12−xNbxO19 (x = 0.00–0.15) was here synthesized by a conventional solid-state reaction method. Thermogravimetry and differential scanning calorimetry curves revealed the sample reactions at four temperature ranges, and the optimal reaction stability was obtained at 1240 °C. A [...] Read more.
SrFe12−xNbxO19 (x = 0.00–0.15) was here synthesized by a conventional solid-state reaction method. Thermogravimetry and differential scanning calorimetry curves revealed the sample reactions at four temperature ranges, and the optimal reaction stability was obtained at 1240 °C. A single-phase polycrystalline form of SrFe12O19 was obtained until the substitution reached 0.09, and the average crystallite size was found to be in the range of 44.21–60.02 nm. According to Fourier-transform infrared spectra, the formation of Fe–O bonds occurred at 69 and 450 cm−1 in the M-type ferrite, while Raman spectra revealed that all the peaks in the sample corresponded to Raman vibration modes and M-type structures. Through the shift of the peaks, it is speculated that Nb5+ enters into the lattice. The hysteresis loops of the samples were measured by vibrating-sample magnetometry, and the calculated results demonstrated that the coercivity increased with increases in the doping amount (686.3 Oe). At the same time, the saturation magnetization remained at a large value (>72.49 emu/g), which has rarely been reported. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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9 pages, 9077 KiB  
Article
Enhanced Coercivity of Low-Density Barium Hexaferrite Magnets from Paste-Injection Molding
Magnetochemistry 2022, 8(4), 46; https://doi.org/10.3390/magnetochemistry8040046 - 15 Apr 2022
Cited by 2 | Viewed by 1813
Abstract
Ceramic–polymer paste-injection molding is demonstrated as a facile fabrication route for barium hexaferrite magnets. Interestingly, these low-density (1.90–2.35 g/cm3) magnets exhibit substantial coercivity of 3868–4002 Oe. When ceramic paste without polymeric additives is used, reduced coercivity and slightly increased magnetizations are [...] Read more.
Ceramic–polymer paste-injection molding is demonstrated as a facile fabrication route for barium hexaferrite magnets. Interestingly, these low-density (1.90–2.35 g/cm3) magnets exhibit substantial coercivity of 3868–4002 Oe. When ceramic paste without polymeric additives is used, reduced coercivity and slightly increased magnetizations are obtained from a magnet with the density of 2.55 g/cm3. Their magnetizations are also higher than those obtained from compactions of sol–gel-derived powders. For compact magnets (3.46–3.77 g/cm3), the DI water addition results in a slightly higher magnetization but lower coercivity than dry-pressed magnets. Compactions into disk and bar magnets give rise to comparable magnetic properties. The morphological characterizations reveal smaller barium hexaferrite particles leading to larger coercivity, and the density and shape of magnets have a less pronounced effect. Full article
(This article belongs to the Special Issue Hexagonal Ferrites: Synthesis, Structure and Properties)
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