Complex Permeability Spectra of Co-Substituted Lithium Zinc Perminvar Ferrite

2008 ◽  
Vol 368-372 ◽  
pp. 591-593
Author(s):  
Hong Jie Zhao ◽  
Ji Zhou ◽  
Long Tu Li
Keyword(s):  
Domain Wall ◽  
Annealing Treatment ◽  
Annealed Sample ◽  
Complex Permeability ◽  
Frequency Range ◽  
Solid Reaction ◽  
Polycrystalline Ferrite ◽  
Co Substitution ◽  
Wall Movement ◽  
Resonance Character

The effect of Co-substitution on the complex permeability of LiZn ferrite was studied. The polycrystalline ferrite samples with a composition of ((Li0.5Fe0.5)0.8Zn0.2)1-xCoxFe2.05O4, where x varies from 0 to 0.08, were prepared by solid-reaction method. The sintered samples were annealed at 490oC for 96 h to produce perminvar effect. The complex permeability was measured in the frequency range from 1 MHz to 2 GHz. The Co-substitution can enhance the real part of complex permeability (μ’). The maximum μ’ appears when x=0.02. The Co-substituted LiZn samples, especially for x=0.02 and 0.04, present resonance-type magnetic spectra obviously. The μ’ of the sample for x=0.02 increases because the damping of domain wall movement decreases after the annealing treatment. The resonance character of the annealed sample becomes even more remarkable due to its domain wall stabilization.

Circumferential permeability in nonmagnetostrictive amorphous wires

1996 ◽  
Vol 11 (10) ◽  
pp. 2486-2489 ◽  
Author(s):  
M. L. Sanchez ◽  
R. Valenzuela ◽  
M. Vazquez ◽  
A. Hernando
Keyword(s):  
Domain Wall ◽  
Current Amplitude ◽  
Complex Permeability ◽  
Equivalent Circuits ◽  
Magnetization Curves ◽  
Frequency Range ◽  
Impedance Response ◽  
Amorphous Wires ◽  
Circular Field ◽  
Magnetization Processes

Real and imaginary components of the impedance response on Co68.1Fe4.4B15Si12.5 amorphous as-cast wires were measured in the 100 Hz-100 kHz frequency range and 0.05–30 mA (RMS) current amplitude, at axial dc fields of 0 and 4800 A/m. From these data, plots of circumferential complex permeability as a function of circular field, as well as magnetization curves, were derived. Results are analyzed in terms equivalent circuits, which allows a resolution of domain wall and rotational contributions to the circumferential magnetization processes.

scholarly journals Fabrication and Electromagnetic wave absorption Properties of Co-Cu-substituted Ni-Zn Spinel Ferrite-epoxy Composites

2020 ◽  
Vol 58 (12) ◽  
pp. 887-895
Author(s):  
Ji-Eun Yoo ◽  
Young-Min Kang
Keyword(s):  
Spinel Ferrite ◽  
Sol Gel ◽  
Complex Permeability ◽  
Ferrite Powder ◽  
Frequency Range ◽  
Absorption Properties ◽  
High Frequency Region ◽  
Wave Absorption ◽  
Co Substitution ◽  
Average Grain Size

Spinel ferrites (Ni0.5Zn0.5)1-<i>x-y</i>Co<i>x</i>Cu<i>y</i>Fe2O4, (<i>x</i> = 0 and <i>y</i> = 0, <i>x</i> = 0.2 and <i>y</i> = 0, <i>x</i> = 0.1 and <i>y</i> = 0.1, <i>x</i> = 0 and <i>y</i> = 0.2) were prepared by sol-gel method and post-annealed at 1100 <sup>o</sup>C. The grain growth of the sample is very sensitive to the Cu substitution <i>y</i>. The average grain size of the non-doped sample (<i>x</i> = 0, <i>y</i> = 0) was ~400 nm and it increased to ~3 μm at the sample with <i>x</i> = 0 and <i>y</i> = 0.2. The real and imaginary parts of permittivities (<i>ε', ε"</i>) and permeabilities (<i>μ', μ"</i>) were measured on the spinel ferrite powder-epoxy (10 wt%) composite samples by a network vector analyzer in the frequency range of 0.1 ≤ <i>f</i> ≤ 15 GHz. The <i>μ'</i> and <i>μ"</i> depend on Co substitution <i>x</i> and the <i>ε'</i> is sensitive to Cu doping <i>y</i>. Reflection loss (RL), which implies electromagnetic (EM) wave absorption properties, were analyzed based on the complex permeability, permittivity spectra. In the RL map plotted as functions of sample thickness (<i>d</i>) and frequency (<i>f</i>), the intensive EM absorbing area (RL < -30 dB) shifted to a high frequency region with increasing Co substitution. This can be attributed to a permeability spectra shift, due to the increase in ferromagnetic resonance frequency produced by the Co substitution. The samples with <i>x</i> = 0.1 and <i>y</i> = 0.1, <i>x</i> = 0.2 and <i>y</i> = 0 also exhibited a very broad-ranged EM wave absorbing performance with a <i>d</i> < 3 mm, indicated by RL < -10 dB being satisfied in the frequency range 7~14 GHz.

Electromagnetic Properties of Silica-Coated Planar Anisotropy Carbonyl-Iron Particles in Quasimicrowave Band

2010 ◽  
Vol 160-162 ◽  
pp. 962-967 ◽  
Author(s):  
Rui Han ◽  
Xiang Hua Han ◽  
Liang Qiao ◽  
Tao Wang ◽  
Fa Shen Li
Keyword(s):  
Carbonyl Iron ◽  
Low Frequency ◽  
Electromagnetic Properties ◽  
Complex Permeability ◽  
Frequency Range ◽  
Planar Anisotropy ◽  
Amorphous Sio2 ◽  
Microwave Absorption Properties ◽  
Sio2 Particles ◽  
Minimum Reflection Loss

For the sake of thinner electromagnetic wave absorbers used in quasimicrowave band, planar anisotropy carbonyl-iron (PACI) coated with amorphous SiO2 particles as absorber and paraffin as matrix were prepared. The complex permeability, complex permittivity and microwave absorption properties were investigated in the frequency range of 0.1-18 GHz. Both the real parts of permeability and permittivity are increased with the increasing of PACI/SiO2 particles volume concentrations. The minimum reflection loss shifts to the low frequency region with increase in PACI/SiO2 particles volume concentrations. The decrease of matching frequency could be well explained by the increasing of and . The PACI/SiO2 core-shell material exhibits great potential in application absorbers in quasimicrowave frequency range.

scholarly journals Magnetic and Microwave Properties of Polycrystalline Gadolinium Iron Garnet

2017 ◽  
Vol 268 ◽  
pp. 287-291 ◽  
Author(s):  
Farah Nabilah Shafiee ◽  
Raba’ah Syahidah Azis ◽  
Ismayadi Ismail ◽  
Rodziah Nazlan ◽  
Idza Riati Ibrahim ◽  
...  
Keyword(s):  
Magnetic Loss ◽  
Ambient Air ◽  
High Energy ◽  
Microwave Properties ◽  
Complex Permeability ◽  
Frequency Range ◽  
Mixed Powder ◽  
Band Frequency ◽  
Suitable Material ◽  
Microwave Loss

The microwave loss in nanosized GdIG particles synthesized using mechanical alloying technique was investigated. There were very few of research on the microwave properties of nanosized particle GdIG and there is no attempt investigating on the material at C-band frequency range and its correlation with the microstructure. Gadolinium (III) iron oxide and iron (III) oxide, α-Fe2O3 were used as the starting materials. The mixed powder was then milled in a high-energy ball mixer/mill SPEX8000D for 3 hours. The samples were sintered at temperature 1200°C for 10 hours in an ambient air environment. The phase formation of the sintered samples was analyzed using a Philips X’Pert Diffractometer with Cu-Kα radiation. Complex permeability constitutes of real permeability and magnetic loss factor were measured using an Agilent HP4291A Impedance Material Analyzer in the frequency range from 10 MHz to 1 GHz. A PNA-N5227 Vector Network Analyzer (VNA) was used to obtain the information on ferromagnetic linewidth broadening, ΔH that represents the microwave loss in the samples in in frequency range of 4 to 8 GHz (C-band). The ΔH value was calculated from the transmission (S21) data acquired from VNA. The single phase GdIG showed low initial permeability and low magnetic loss when applied with low-frequency range energy. From these data, it is validated that GdIG is a suitable material for microwave devices for the high-frequency range.

Coercivity Mechanism in Hard and Soft Sintered Magnetic Materials

2014 ◽  
Vol 802 ◽  
pp. 563-568 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Grain Size ◽  
Domain Wall ◽  
Magnetic Materials ◽  
Wall Thickness ◽  
Magnetic Behavior ◽  
Soft Magnetic Materials ◽  
High Coercivity ◽  
Soft Magnetic ◽  
Hard Magnetic Materials ◽  
Wall Movement

The coercivity in soft and hard magnetic materials has different origin. The high coercivity of barium ferrite, SmCo5, Sm2Co17or Nd2Fe14B is due to high magnetocrystalline anisotropy, and the processing aims very small grain size (nanocrystalline). In the case of soft magnetic materials, the coercivity has origin in defects that are able to stop domain wall movement, as for example grain boundaries, inclusions or dislocations. Soft magnetic materials in general present large domain wall thickness (thousands of Angstroms for pure iron), whereas domain wall thickness is ~ 50 Angstroms for SmCo5and Nd2Fe14B. The differences between hard and soft magnetic behavior are commented and discussed. The domain wall energy and thickness can be used as parameters for classifying soft and hard magnetic behavior. Other examples of soft magnetic materials are the amorphous alloys and the nanocrystalline soft magnetic materials with grain size very below the single domain particle size. The soft behaviour in amorphous and soft nanocrystalline materials is also discussed.

Frequency Dependence of Complex Permeability of Polycrystalline Ferrites Based on the Realities of Microstructure

2013 ◽  
Vol 543 ◽  
pp. 507-510 ◽  
Author(s):  
Janis Jankovskis ◽  
Nikolajs Ponomarenko ◽  
Deniss Stepins
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Frequency Dependence ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Complex Permeability ◽  
Absorption Component ◽  
Resonance Character ◽  
Explicit Relation

Complex permeability spectra of polycrystalline ferrites are analyzed on the basis of the model accounting for the effects of their grain size distribution (GSD). The model allows for explicit relation for absorption component. It shows, that by change of only one parameter (related with GSD) it is possible to turn from the relaxation to resonance character of spectrum, that spectra of ferrites, sintered at low temperature, tend to the most theoretical type - symmetrical one.

SiC Micro-Threads Prepared within the Carbon Fiber Felt

2008 ◽  
Vol 368-372 ◽  
pp. 843-845
Author(s):  
Feng Yuan ◽  
Hong Jie Wang ◽  
Zhi Hao Jin
Keyword(s):  
Carbon Fiber ◽  
Three Dimensional ◽  
Nitrogen Pressure ◽  
Complex Permeability ◽  
Similar Form ◽  
Frequency Range ◽  
Band Frequency ◽  
X Band ◽  
Carbon Fiber Felt ◽  
Low Nitrogen

Polyacrylonitrile (PAN) based carbon fiber felt which contains abundant various SiC microthreads and some other microstructures was prepared through sintering the pretreated felt at high temperature at low nitrogen pressure. XRD, SEM, TEM, HRTEM analyses for the sintered felt were carried out to study its components and microstructures. There are SiC nanothreads, SiC submicron threads, SiC micron threads and a few SiO2 two- or three-dimensional microstructures (possibly intermix with the similar form of SiC) existed within the inner hollow spaces of the felt. The complex permittivity, complex permeability of the sample in the X-band frequency range were obtained.

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