The Temperature Behavior of Resonant and Non-resonant Microwave Absorption in Ni-Zn Ferrites

Valenzuela, R.

doi:10.5772/16508

Cited by 10 publications

(4 citation statements)

References 23 publications

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“…Similarly, the ferromagnetic resonance peak at higher frequencies takes place at 6.55 GHz in the S1 ferrite and shifts to 7 GHz in S2 and 8.05 GHz in S3. Since the resonance frequency is proportional to an effective internal field, the higher corresponds with a stronger internal field due to the demagnetization effects rising from the porosity and the finer grains [20,21]. The shift of the spectrum towards higher frequencies is accompanied by the reduction of the respective permeability levels, which is in accordance with fundamental Snoek's law defining the product ( − 1) × [3].…”

Section: Static Magnetic Propertiessupporting

confidence: 60%

Microstructure and Electromagnetic Properties of Ni-Zn-Co Ferrite up to 20 GHz

Stergiou

2016

Advances in Materials Science and Engineering

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The present paper examines the relation between different developed microstructures and the microwave electromagnetic properties in Ni-Zn-Co ferrite. To this end, the Ni0.25Zn0.25Co0.5Fe2O4composition has been prepared with the conventional ceramic process with varied prefiringTP(750°C, 1000°C) and sinteringTStop temperatures (1200°C, 1250°C). When lower temperatures are applied in these production stages, incomplete microstructures with low density, higher porosity, or finer grains are achieved. On account of these features, the contributions of domain wall motion and spin rotation to the complex permeabilityμ⁎(f)move to higher frequencies, whereas microwave dielectric permittivityε⁎(f)is decreased. In particular in conjunction with the high Co content, the wall relaxation and spin resonance are interestingly forced to occur at 850 MHz and 8.05 GHz, respectively. Regarding the electromagnetic wave attenuation, the ferrite annealed at lower temperatures exhibits strong return loss peaks at higher frequencies, but without other performance improvement. We should notice that the variations in sintering temperatureTSyield the maximum changes in the recorded parameters, including the coercive field,μ⁎(f),andε⁎(f), indicating the inferior role of prefiringTPin Ni-Zn ferrite.

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Section: Static Magnetic Propertiessupporting

confidence: 60%

Microstructure and Electromagnetic Properties of Ni-Zn-Co Ferrite up to 20 GHz

Stergiou

2016

Advances in Materials Science and Engineering

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“…ions having a strong preference to occupy A-sites leads to mixed spinel structure whose cation distributions are normal with respect to Zn and inverse from the viewpoint of Ni spinel structure [1][2][3]. In case of Zn, Cu and Co substituted Ni ferrite with chemical composition Nil_x_y_zZnxCuyCozFe 2 04 IOns occupy A-and B-sites in agreement with alignment…”

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confidence: 51%

Magnetic properties of Ni ferrites substituted by divalent Zn, Cu and Co ions

2014

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Substituted Ni ferrite samples with chemical composition Nil_x_ Y _ Z ZnxCuyCozFe204, where x = 0.4, 0.5 and 0.6, y = 0.1, z = 0.01 and 0.02 were prepared by classical ceramic technology at the temperature of 1200°C. The influence of divalent Zn, Cu and Co ions substitution on the magnetic properties of spinel Ni ferrites was studied. The magnetic properties, such as the Curie temperature, coercive field, remanent magnetic flux density, hysteresis loop area as well as the amplitude and initial permeability were investigated by means of thermo-magnetic analysis and magnetisation curves measurements at low frequencies. 1. INTRODUCTION NiZnCuCo ferrites belong to ferrimagnetic ceramic materials with spinel, i.e. cubic structure of dominant ionic nature. The elementary cell consists of 8 ferrite molecules containing in total 32 0-anions and 24 metallic cations where the metallic cations occupy the tetrahedral (A) or the octahedral (B) sublattice. The simplest 2-3 spinels comprise of divalent and trivalent cations. The spinel with normal cation distribution is characterised by divalent cations occupying tetrahedral A sites and trivalent cations occupying octahedral B-sites. When the trivalent cations occupy tetrahedral A-sites and the divalent and remaining trivalent cations are presented in octahedral B sites we speak of inverse cation distribution. This alignment is characterised for nickel ferrite NiFe z 04 with cation distribution (Fe3+)A[Ni z +Fe3+]BOl-. The substitution of Ni2+ ions by Zn2+ ions having a strong preference to occupy A-sites leads to mixed spinel structure whose cation distributions are normal with respect to Zn and inverse from the viewpoint of Ni spinel structure [1-3]. In case of Zn, Cu and Co substituted Ni ferrite with chemical composition Nil_x_y_zZnxCuyCozFe 2 04 IOns occupy A-and B-sites in agreement with alignmentThese materials appear to be perspective for high-frequency applications -as such they are extensively studied, see e.g. [3].

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“…The change of molar ratios and consisting in the reduction of ions caused increase of , but the magnetic properties got worse. This magnetic behavior of ferrite samples is caused by redistribution of ions within tetrahedral and octahedral sublattices of spinel structure and the variations of the super-exchange interactions in these sublattices [6], [7]. The Curie temperature of the sample with the highest value of initial permeability is too low for practical use.…”

Section: Resultsmentioning

confidence: 96%

Magnetopolymer Composites With Soft Magnetic Ferrite Filler

et al. 2013

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Thanks to their good magnetic properties, NiZn ferrites can be used as the soft magnetic filler in magneto-polymer composites. The ferrites having general composition ( , 0.33, 0.36, 0.42, and 0.50) were prepared by means of ceramic method and the magnetic properties, such as initial permeability and Curie temperature were investigated. The sample with composition having and was chosen as the filler for magneto-polymer composites. The aim of the work was the study of preparation and properties of magnetic polymer composites based on natural rubber SMR 20 in a wide range of concentrations (0-600 phr). The influence of ferrite content on magnetic, physical-mechanical and rheological properties of prepared composites was investigated. The effect of the concentration of ferrite filler on the complex permeability of the composites in the frequency range from 10 MHz to 3 GHz as well as the physical-mechanical and rheological properties is evident.

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The Temperature Behavior of Resonant and Non-resonant Microwave Absorption in Ni-Zn Ferrites

Cited by 10 publications

References 23 publications

Microstructure and Electromagnetic Properties of Ni-Zn-Co Ferrite up to 20 GHz

Microstructure and Electromagnetic Properties of Ni-Zn-Co Ferrite up to 20 GHz

Magnetic properties of Ni ferrites substituted by divalent Zn, Cu and Co ions

Magnetopolymer Composites With Soft Magnetic Ferrite Filler

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