Structural and magnetic characterization of Y-type hexaferrite powders prepared by sol-gel auto-combustion and sonochemistry

Georgieva, Borislava; Kolev, Svetoslav; Krezhov, K.; Ghelev, Chavdar; Kovacheva, Daniela; Vertruyen, Bénédicte; Closset, Raphael; Tran, Lan Maria; Babij, M.; Zaleski, A.; Koutzarova, T.

doi:10.1016/j.jmmm.2019.01.033

Cited by 10 publications

(6 citation statements)

References 21 publications

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“…Thus, one might speculate that the external magnetic field changes the samples’ permeability to negative or positive [ 47 ], depending on whether the material’s resonance frequency is above or below the frequency range of the measurement. Additionally, for all of the samples, a magnetic phase transition from a helicoidal to a ferrimagnetic spin order occurs around room temperature, which was demonstrated in our earlier study [ 31 , 34 ]. This could play an important role in determining the microwave characteristics under an external magnetic field.…”

Section: Resultssupporting

confidence: 71%

“…These clusters are randomly distributed in the volume of the toroidal samples. Our previous investigations have shown that the average particle size is around 600 nm, with the size being within the 200–1000-nm range [ 34 ]. Since the same synthesis technique was used for all of the samples, it was only natural to assume that all of them would have a broad particle size distribution.…”

Section: Resultsmentioning

confidence: 99%

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Magnetic Field Influence on the Microwave Characteristics of Composite Samples Based on Polycrystalline Y-Type Hexaferrite

et al. 2022

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Here, we report results on the magnetic and microwave properties of polycrystalline Y-type hexaferrite synthesized by sol-gel auto-combustion and acting as a filler in a composite microwave-absorbing material. The reflection losses in the 1–20 GHz range of the Y-type hexaferrite powder dispersed homogeneously in a polymer matrix of silicon rubber were investigated in the absence and in the presence of a magnetic field. A permanent magnet was used with a strength of 1.4 T, with the magnetic force lines oriented perpendicularly to the direction of the electromagnetic wave propagation. In the case of using an external magnetic field, an extraordinary result was observed. The microwave reflection losses reached a maximum value of 35.4 dB at 5.6 GHz in the Ku-band without a magnetic field and a maximum value of 21.4 dB at 8.2 GHz with the external magnetic field applied. The sensitivity of the microwave properties of the composite material to the external magnetic field was manifested by the decrease of the reflected wave attenuation. At a fixed thickness, tm, of the composite, the attenuation peak frequency can be adjusted to a certain value either by changing the filling density or by applying an external magnetic field.

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Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Magnetic Field Influence on the Microwave Characteristics of Composite Samples Based on Polycrystalline Y-Type Hexaferrite

et al. 2022

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“…The average thickness of the Ba 2 Mg 2 Fe 12 O 22 particles was 380 nm. A similar microstructure was observed for Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 . , …”

Section: Synthesis Techniques Of Y-type Hexaferritessupporting

confidence: 79%

“…The precursors produced by these co-precipitation methods are synthesized at 1170 °C. We described in detail such a procedure for the synthesis of different Y-type hexaferrites. − We also reported , a comparative investigation on this synthesis method’s effect on the microstructural and magnetic parameters of Ba 2 Mg 2 Fe 12 O 22 powder materials and found that the ultrasonically assisted co-precipitation produced particles with a practically perfect hexagonal shape compared with the particles obtained by sol–gel autocombustion (Figure b). The average thickness of the Ba 2 Mg 2 Fe 12 O 22 particles was 380 nm.…”

Section: Synthesis Techniques Of Y-type Hexaferritesmentioning

confidence: 99%

“…A similar microstructure was observed for Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 . 43,44 We should note that the process of preparation is not the only factor affecting the powders' microstructure; the latter changes upon substituting the metal cations, as well. For example, in the studies on the effect of Al substitution in the Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 hexaferrite system, a melting process was observed to take place during the synthesis of the substituted Ba 0.5 Sr 1.5 Zn 2 Al 0.08 Fe 11.92 O 22 hexaferrite by sol−gel autocombustion (Figure 3).…”

Section: Hexaferritesmentioning

confidence: 99%

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Phase Transitions in Magneto-Electric Hexaferrites

et al. 2022

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Hexaferrites have long been the object of extensive studies because of their great possibility for applications�permanent magnets, highdensity recording media, microwave devices, in biomedicine, to name but a few. Lately, many researchers' efforts have been focused on the existence of the magneto-electric effect in some hexaferrite systems and the appealing possibility of them being used as single-phase multiferroic and magnetoelectric materials. As indicated by theoretical analyses, the origin of the large magneto-electric effect can be sought in the strong interaction between the magnetization and the electric polarization that coexist in insulators with noncollinear magnetic structures. The hexaferrites' magnetic structure and, particularly, the specific magnetic spin ordering are the key factors in observing magneto-electric phases in hexaferrites. Some of these phases are metastable, which hampers their direct practical use. However, as the hexaferrites' phase diagrams reveal, chemical doping can be used to prepare a number of noncollinear stable magnetic phases. Since the magneto-electric effect has to do with the magnetic moments ordering, it seems only logical that one should study the cation substitutions' influence on the magnetic phase transition temperature. In this paper, we summarize recent examples of advances in the exploration of magnetic phase transitions in Y-type hexaferrites. In particular, the effect is emphasized by substituting in Y-type hexaferrites the nonmagnetic Me 2+ cations with magnetic ones and of the magnetic Fe 3+ cations with nonmagnetic ones on their magnetic properties and magnetic phase transitions. The work deals with the structural properties of and the magnetic phase transitions in a specific Y-type hexaferrite, namely, Ba(Sr) 2 Me 2 Fe 12 O 22 .

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Magnetic ferrites

Ghasemi¹

2022

Magnetic Ferrites and Related Nanocomposites

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Structural and magnetic characterization of Y-type hexaferrite powders prepared by sol-gel auto-combustion and sonochemistry

Cited by 10 publications

References 21 publications

Magnetic Field Influence on the Microwave Characteristics of Composite Samples Based on Polycrystalline Y-Type Hexaferrite

Magnetic Field Influence on the Microwave Characteristics of Composite Samples Based on Polycrystalline Y-Type Hexaferrite

Phase Transitions in Magneto-Electric Hexaferrites

Magnetic ferrites

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