Electromagnetic characterization of Ni0.5Zn0.3Co0.2Fe2O4 bulk ceramics in the 1MHz-12GHz frequency range

In this paper, NiZnCo ferrite was produced by solid state synthesis, calcination at 1000?C and sintering at 1250?C in air atmosphere. The microstructure and phases of the sintered sample were analysed by scanning electron microscopy and X-ray diffraction, respectively. The magnetic properties of the ferrite were evaluated by magnetization and magnetostriction measurements. The complex magnetic permeability and complex permittivity were also measured between 1MHz-12GHz and the reflection loss (RL) was calculated in the 100MHz-12GHz frequency range. The results show that the ferrite sample presents magnetostrictive behaviour and a saturation magnetization of 71 Am2/kg. Complex permittivity measurements indicate that the material has dielectric behaviour in the whole frequency range studied, with "? varying between 7-40, and magnetic behaviour in frequencies between 1MHz-5GHz. The minimum RL was found at frequencies between 2.4-3.3GHz and the calculated RL value for a thickness of 3mm was lower than ?10 dB in frequencies between 2.3-7.3GHz. These results indicate potential application as microwave absorber in the S band.

Facile co-precipitation route for magnesium ferrites nanostructure: Synthesis, influence of pH variation on structural properties

This report presents the synthesis of magnesium ferrite (MgFe2O4) by coprecipitation method and its subsequent characterization by using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. XRD results confirm the formation of single phase cubic spinel structure, having lattice constant from 8.3216 ? to 8.3252 ?. An infrared spectroscopy study confirms the presence of two main absorption bands indicating tetrahedral and octahedral group complexes, within the spinel lattice. We also report hopping length (LA and LB), strain (?) and dislocation density (?D) of ferrite sample.

The evaluation of kinetic parameters for cadmium doped Co-Zn ferrite using thermogravimetric analysis

This work had the objective to analyze the thermodynamic properties of cadmium doped cobalt zinc ferrite (Co0.5Zn0.5Cd0.3Fe1.8O4), obtained by solid state reaction method and characterized by TGA-DTA. The TG analysis show sharp peaks at four points, two for water reduction, one for decomposition of chlorides and last one for formation of end product. The ratio of weight of end product to starting material match with ratio of molecular weight of end product and starting materials; this confirms the formation of ferrite sample. Broido, Coats-Redfern, Chang and Horowitz-Metzger approximations are employed to compute the activation energy (Ea) of formation of ferrite sample. The kinetic parameters like frequency factor (A), entropy change (ΔS), enthalpy change (ΔH) and changes in internal energy (ΔG) of sample are also reported.

Synthesis and Structural Investigation of Nano-Sized Cadmium Ferrite

This report presents the synthesis of cadmium ferrite (CdFe2O4) by Oxalate co-precipitation and its subsequent characterization by using X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) techniques. XRD results confirm the single cubic spinel phase formation with lattice parameter 8.7561Ao. An infrared spectroscopy study shows the presence of main two absorption bands indicating the presence of tetrahedral and octahedral group complexes, respectively, within the spinel lattice. We also report strain, hopping length (LA and LB) and dislocation density of ferrite sample.

On the Structure and Some Properties of LaCo Co-substituted NiZn Ferrites Prepared Using the Standard Ceramic Technique

Zn0.5Ni0.5-xCoxFe2-yLayO4 ferrites (with x=0, 0.02 and y=0, 0.02) were prepared by an industrial method using the standard ceramic technique and sintered at 1,250°C in air. X-ray diffraction (XRD) was used to obtain the phase formation of the NiZn ferrites. The microstructure of ferrites was investigated by scanning electron microscopy (SEM). The XRD reveals that lattice parameter (a) is decreased and a secondary phase (LaFeO3) is formed in the La–Co co-substituted NiZn ferrite sample, meanwhile, the grain size (D) of this sample decreased obviously by observing SEM photographs. Vibrating sample magnetometry (VSM), B-H analyzer, impedance analyzer and electrometer were carried out in order to characterize some properties of the ferrites. This investigation indicates that, La–Co co-substituted NiZn ferrite sample has higher power loss (Pcv) than other samples at low frequency with an increase in coercive field (Hc) and magnetocrystalline anisotropy (K1), a decrease in initial permeability (μi) and saturation magnetization (Ms). However, at high frequency, the power loss of La–Co co-substituted sample is low, which is attributed to high resistivity (ρ), small grain size (D), less number of Fe2+ ions and low porosity (P).

Effect of Mechanical Milling on the Magnetic Properties of SrFe12O19

In this work, a single phase strontium ferrite sample was mechanically milled for 60 h. It has been found that the crystallite size reduced by 85%. A dramatic drop (from 4500 to 1600 Oe) in the coercive filed was also observed. The observed reduction in the coercivity was attributed to the reduction of the single domain particle size.

Microwave Absorption Characteristics of some Ferrite-Filled Polymer Composites

Prior to their use for microwave absorption, different compositions of NixZn1-xFe2O4 (x = 0.5, 0.6, 0.7 and 0.8) were prepared via mechanical alloying and sintering. X-ray diffractometry (XRD) was used to investigate the crystalline phase formation. Scanning transmission electron microscopy (STEM) and field emission electron microscopy (FeSEM) were used to investigate the particle size and surface morphology respectively. The complex-permeability components, μʹ and μʺ, were also measured using an Agilent 4291B material analyzer from 1 MHz to 1 GHz. From the XRD results it is shown that at 900oC the full phase of nickel zinc ferrite was formed. The μʺ values suggest that the ferrite sample can absorb well microwave energy for frequencies 1 MHz to 1 GHz and higher. This is proved by microwave absorption measurements carried out up to 12 GHz.Keywords: NiZn-ferrite, microwave absorption, magnetic materials

High Frequency Characteristic of Elements Substituted Hexagonal Ferrites

The initial permeability μ' (at 0.1 GHz) of Ba3Co2R0.1Fe23.9O41 (x=0.1, R= Gd, Dy, Ho, Yb) samples is higher than that of the Co2Z ferrite without substitution. In particular, μ' of Gd3+ substituted Z-type ferrite sample (x=0.1) is the highest of all samples. The substituted sample of Ba3Co2TixZnxFe24-2xO41 with x= 0.85 has a maximumμ' of 24, which is twice as large as that of the non-substituted sample with x=0. Ba3Co2-2x LixFe24+xO41(x=0-1.0) are also prepared. The sample with x=0 showsμ'of 8 at 50MHz. The maximumμ' is 24.5 at x=0.3. An apparent magnetic anisotropy constant K*, calculated by using HA* and MS, decreases. Therefore, the decrease of the magnetic anisotropy contributes to the increase of μ'.