Grain-size effects on microwave ferrite magnetic properties

Inui, T.; Ogasawara, N.

doi:10.1063/1.324782

Cited by 17 publications

(7 citation statements)

References 41 publications

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“…The increase is generally attributed to some aspects of the microstructure, such as porosity, grain size, grain size distribution, or anisotropy in the randomly oriented crystallites. 9,14 On the other hand, the off-resonance effective linewidth, especially at high field, is not affected by two-magnon scattering and can be much smaller. The spin wave linewidth represents the relaxation rate of the renormalized spin wave modes that exhibit a threshold loss effect under parametric excitation.…”

Section: Microwave Linewidth Parameters and Measurement Overviewmentioning

confidence: 99%

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Назаров¹,

Ménard²,

Green³

et al. 2003

Journal of Applied Physics

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Unusual metallic behavior in nanostructured cobalt ferrite at superparamagnetic regime J. Appl. Phys. 112, 063926 (2012) Investigation of structural, dielectric, and magnetic properties of hard and soft mixed ferrite composites J. Appl. Phys. 112, 054323 (2012) Magneto-optical study of holmium iron garnet Ho3Fe5O12 Low Temp. Phys. 38, 863 (2012) Growth and ferromagnetic resonance of yttrium iron garnet thin films on metalsThe ferromagnetic resonance ͑FMR͒ linewidth, the field dependent effective linewidth, and the parallel pump spin wave linewidth were measured for spheres and disks prepared from a block of hot isostatic pressed ͑hipped͒ polycrystalline yttrium iron garnet ͑YIG͒. All linewidths as well as static magnetization data indicate close to 100% density. Vibrating sample magnetometer measurements give an average saturation induction 4M s of 1825 G. The FMR half-power linewidths for the spheres at 9.5 GHz were 13 Oe. Linewidths measured over the 9.5-18 GHz frequency range show a small but distinct drop and agree with Schlömann's theory of anisotropy-dominated two-magnon scattering for polycrystalline ferrites. The effective linewidth versus field data at 10 GHz show a region of strong absorption that corresponds to the width of the spin wave manifold for low wave numbers and a high field value of about 2 Oe. Parallel pumping measurements give minimum spin wave linewidths of 1.2 and 0.6 Oe at 9 and 16.7 GHz, respectively. The 16.7 GHz spin wave linewidths correspond to half-frequency spin waves at 8.35 GHz. The extrapolated linewidths at zero wave number are about 0.5 Oe and match the established intrinsic linewidths expected for YIG single crystals at 8 -9 GHz. The spin wave linewidths increase linearly with wave number and are consistent with a transit time scattering process with scattering lengths that are about ten times greater than the average grain size.

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Section: Microwave Linewidth Parameters and Measurement Overviewmentioning

confidence: 99%

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Назаров¹,

Ménard²,

Green³

et al. 2003

Journal of Applied Physics

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“…Pal et al [32] reported high coercivity in soft spinel ferrite materials with nanosized dimensions as compared to that in micron-sized ones. Inui and Ogasawara [33] found the inverse proportion of coercivity to grain size in multidomain grains. This is because the enlargement of the grains takes place with increasing sintering temperature in such a way that the larger grains contain more domain walls, enhancing the wall movement contribution to magnetization or demagnetization [33,34].…”

Section: Resultsmentioning

confidence: 98%

“…Inui and Ogasawara [33] found the inverse proportion of coercivity to grain size in multidomain grains. This is because the enlargement of the grains takes place with increasing sintering temperature in such a way that the larger grains contain more domain walls, enhancing the wall movement contribution to magnetization or demagnetization [33,34]. In fact, wall movement requires a lower energy than the rotation of domains.…”

Section: Resultsmentioning

confidence: 98%

Effects of Milling Atmosphere and Increasing Sintering Temperature on the Magnetic Properties of Nanocrystalline Ni_0.36Zn_0.64Fe₂O₄

Hajalilou

Hashim

Kamari

et al. 2015

Journal of Nanomaterials

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Nanocrystalline Ni0.36Zn0.64Fe2O4was synthesized by milling a powder mixture of Zn, NiO, and Fe2O3in a high-energy ball mill for 30 h under three different atmospheres of air, argon, and oxygen. After sintering the 30 h milled samples at 500°C, the XRD patterns suggested the formation of a single phase of Ni-Zn ferrite. The XRD results indicated the average crystallite sizes to be 15, 14, and 16 nm, respectively, for the 30 h milled samples in air, argon, and oxygen atmospheres sintered at 500°C. From the FeSEM micrographs, the average grain sizes of the mentioned samples were 83, 75, and 105 nm, respectively, which grew to 284, 243, and 302 nm after sintering to 900°C. A density of all the samples increased while a porosity decreased by elevating sintering temperature. The parallel evolution of changes in magnetic properties, due to microstructural variations with changes in the milling atmosphere and sintering temperature in the rage of 500–900°C with 100°C increments, is also studied in this work.

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“…Large grain size reduces the number of grain boundaries in the sample and increases initial permeability. Globus proposed a model for initial permeability, in which the domain wall is pinned to grain surface, and reversible wall motion is caused by wall bulging . As per this model, initial permeability varies linearly with grain size and saturation magnetization.…”

Section: Factors Influencing Initial Permeabilitymentioning

confidence: 99%

Engineering High Permeability:Mn–Zn andNi–Zn Ferrites

Kumar¹,

Shinde

Vasambekar

2014

Int J Applied Ceramic Tech

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Magnetic properties of polycrystalline spinel ferrites are of significant interest in scientific community. Of all, initial permeability is most important magnetic property for device fabrication. Mn-Zn and Ni-Zn ferrites are commercially most successful class of ferrites. Ferrites accommodate variety of cations in interstitial sites; type of cations, their occupancy at interstitial sites, grain size, pores, defects, or other imperfections in ferrites regulate their response to external magnetic stimulus. These factors are influenced by composition and preparation method. The failure of initial permeability of ferrites, to withstand variation in frequency of applied signal has fueled intense efforts in scientific community to optimize frequency stability of permeability. Therefore, improvement in their permeability is important from commercial perspective, and it further enables deeper insight into the dynamical link between microstructure and magnetic properties. This work presents a review of initial permeability in Mn-Zn and Ni-Zn ferrites with a focus on influence of intrinsic factors and frequency of applied signal. The work is an analytical assessment to provide framework for engineering high permeability in ferrites.

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Grain-size effects on microwave ferrite magnetic properties

Cited by 17 publications

References 41 publications

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Effects of Milling Atmosphere and Increasing Sintering Temperature on the Magnetic Properties of Nanocrystalline Ni_0.36Zn_0.64Fe₂O₄

Engineering High Permeability:Mn–Zn andNi–Zn Ferrites

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Grain-size effects on microwave ferrite magnetic properties

Cited by 17 publications

References 41 publications

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Near theoretical microwave loss in hot isostatic pressed (hipped) polycrystalline yttrium iron garnet

Effects of Milling Atmosphere and Increasing Sintering Temperature on the Magnetic Properties of Nanocrystalline Ni0.36Zn0.64Fe2O4

Engineering High Permeability:Mn–Zn andNi–Zn Ferrites

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Product

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Effects of Milling Atmosphere and Increasing Sintering Temperature on the Magnetic Properties of Nanocrystalline Ni_0.36Zn_0.64Fe₂O₄