Manganese-based spinel ferrites for microwave absorption (original) (raw)
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Ceramic International, 2019
New yttrium substituted manganese ferrite (MnYxFe2-xO4) nanoparticles (NPs) were prepared by low cost reverse micelle micro-emulsion method by utilizing cheap raw materials like Paraffin, Triton X-100, and 1-butanol and corresponding metal salts. The Y3+content (x) range was kept 0≤x≤0.16. Thermogravimetric analysis (TGA) of un-annealed precipitates was carried out to probe the phase formation temperature. The annealing of precipitates of all compositions of MnYxFe2-xO4 nanoparticles was carried at 400°C for 4h (h). The annealing was carried out under vacuum to control the oxidation of manganese. The effect of Y3+ cations on structural, spectral and dielectric properties was investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy and impedance analyzer measurements at room temperature. XRD patterns confirmed the formation of MnFe2O4 and its derivatives with yttrium. Site radii and bond lengths were calculated from XRD data. FTIR spectra confirmed the tetrahedral (A) and octahedral (B) sites in all compositions of MnYxFe2-xO4 nanoparticles, which is characteristic of spinel ferrites having FCC (face centered cubic) structure. Scanning electron microscopic (SEM) analysis confirmed the spherical morphology of ferrite particles. Dielectric parameters analysis in the frequency range from 1×106Hz to 3×109Hz suggested that these ferrite particles may find their potential applications in high frequency devices fabrication.
Jurnal Teknologi
A research to study the microwave absorption properties of manganese ferrite in the X-band range have been conducted by using high energy milling technique. The synthesis of manganese ferrite (Mn1+xFe2-xO4) was performed using solid state reaction method with the material composition (x)MnO : (2-x) Fe2O3 (x = 0.25; 0.50; 0.75 and 1.0) according to the molar ratio. This powder mixture was being milled for 10 hours then sintered at 1200 °C temperature for 3 hours. Material characterization was done by using FTIR spectroscopy (Fourier Transform Infra Red Spectroscopy) to observe the functional group, XRD (X-ray diffractometer) for phase identification, SEM (Scanning Electron Microscope) for surface morphology observation and VNA (Vector Network Analyzer) to determine the ability of materials to absorb microwaves. Analysis by FTIR showed two absorption peaks in the range of ~ 446 and ~ 557 cm-1 were associated with the octahedral and tetrahedral sites in structure of MnFe2O4. Phase iden...
Electric and dielectric properties of ytterbium substituted spinel ferrites
Journal of Materials Science: Materials in Electronics, 2017
Ytterbium (Yb) substituted magnesium ferrite materials (MgYb x Fe 2−x O 4 with x = 0.00, 0.025, 0.050, 0.075, 0.10) have been prepared by the Sol-gel method. XRD analysis revealed that the prepared samples are cubic spinel with single phase till the content 'x' equals 0.05. At higher content x ≥ 0.075, Yb substituted samples possessed YbFeO 3 phase along with the cubic spinel phase. A significant decrease of ~34.7 nm in crystallite size is noted in response to the increase in Yb substitution level. The room temperature dc resistivity increases gradually from 3.47 × 10 7 to 2.63 × 10 8 Ω-cm as the substitution of Yb is increased. Temperature dependent DC electrical resistivity of all the samples exhibits semiconducting behavior. Yb substituted materials can be suitable to limit the eddy current losses for microwave applications. VSM indicated the existence of an appreciable fraction of ferrimagnetic properties at room temperature. The saturation magnetization of the samples decreases from 60 to 33 emu/g. Saturation magnetization and remanence decreased while coercivity increased with Yb substitution.
Yttrium-substituted Mg–Zn ferrites: correlation of physical properties with Yttrium content
Journal of Materials Science: Materials in Electronics, 2019
Yttrium-(Y) substituted Mg-Zn ferrites with the compositions of Mg 0.5 Zn 0. 5Y x Fe 2-x O 4 (0 ≤ x ≤ 0.05) have been synthesized by conventional standard ceramic technique. The effect of Y 3+ substitution on the structural, electrical, dielectric and magnetic properties of Mg-Zn ferrites has been studied. The single phase of spinel structure with a very tiny secondary phase of YFeO 3 for higher Y contents has been detected. The theoretically estimated lattice constant has been compared with measured experimental lattice constant. The bulk density, X-ray density and porosity have been calculated. The Energy Dispersive X-ray Spectroscopy (EDS) study confirms the presence of Mg, Zn, Y, Fe and O ions in the prepared samples. Frequency dependence of conductivity has been studied and an increase in resistivity (an order) has been observed. Frequency dependence of dielectric constant (ԑʹ), dielectric loss tangent (tanδ) has been studied and the lowering of ԑʹwith the increase of Y content was noted. Dielectric relaxation time was found to vary between 15 to 31 nano seconds. The saturation magnetization (M s), coercive field (H c), remanent magnetization (M r) and Bohr magneton (µ B) have been calculated. The variation of M s has been successfully explained with the variation of A-B interaction strength due to Y substitution. The soft ferromagnetic nature also confirmed from the values of H c. The complex permeability has been studied and the initial permeability was found to increase with Y up to x = 0.01, thereafter it decreases. The values of electrical resistivity and dielectric constant with proper magnetic properties suggest the suitability of Y-substituted Mg-Zn ferrites in microwave device applications.
Development and characterization of nickel-zinc spinel ferrite for microwave absorption at 2·4 GHz
Bulletin of Materials Science, 2008
This paper deals with the development and characterization of nickel-zinc spinel ferrite (Ni (1-δ) Zn δ Fe 2 O 4) for microwave absorption at 2⋅4 GHz (ISM band). The ferrite powder was prepared by dry attrition and sintering process. Complex permittivity and permeability of the prepared sample have been determined by measuring its scattering parameters with the help of a vector network analyser. The measured parameters have been used to determine its wave absorption properties over a frequency range 2⋅1-2⋅6 GHz.
Structural, magnetic and microwave absorption properties of SrFe12−2x(Mn0.5Cd0.5Zr)xO19 ferrite
Journal of Magnetism and Magnetic Materials, 2014
Nanoparticles of Ca(MnSn) x Fe 12À2x O 19 with x ranging from 0.00 to 0.6 in steps of 0.2 were prepared by use of the citrate precursor method. The structural, microwave-absorption, and magnetic properties of these ferrites were determined by use of different characterization techniques. The morphology of the ferrite powders was investigated by transmission electron microscopy (TEM). X-ray diffraction (XRD) was used for structural and micro-structural studies, and revealed that the samples had an M-type hexagonal structure. The crystallite size for each sample was calculated by use of the Scherrer formula for the most intense peak (411) and the results were compared with those obtained from TEM images of the samples. The particle size of the powder varied from 60 to 36 nm. Magnetic measurements were performed by vibrating sample magnetometry (VSM) at room temperature. The microwaveabsorption properties of ferrite (70 wt.%)-polymer (30 wt.%) composites 2 mm thick were investigated by vector network analysis (VNA) in the frequency range 12-20 GHz. The ferrite for which x = 0.4 had a minimum reflection loss of À29 dB at 17.3 GHz with a À15 dB bandwidth over the extended frequency ranges 12.9-14.5 GHz and 16.7-18 GHz. The minimum loss reached À32 dB at frequency of 17 GHz when the total amount of Mn 2+ and Sn 4+ ions was 0.6. These results suggest that the synthesized magnetic composites can be used as effective microwave absorbers in military applications (radar cross-section reduction).
Journal of Physics: Conference Series, 2019
The manganese-natural ferrite anisotropy magnets were prepared via the solid state reaction method with various sintering temperature of 900, 1000 and 1100 C for 3 hours. This process were performed by doping MnO2 on fe2O3 natural ferrite. XRD, VSM and VNA Characterizations were carried out to investigate the effects of sintering temperature on structure, magnetic properties and microwave absorption capability. The characterization results showed that sintering temperature affect on microstructure, particle size and crystalline phase. Furthermore, the magnetic properties including the saturation magnetization value (Ms), and the remanent magnetization (Mr) increase, while the coercivity field value (Hc) decreases with the rise of sintering temperature. In addition, Manganese ferrites sintered at 1000 C exhibit magnificent microwave absorption capability with an average value of reflection loss-10.98 dB at 10.78 GHz. These superior materials is believed to be promising materials for microwave application in GHz range.
Study of spinel ferrites with addition of small amount of metallic elements
Journal of Electroceramics
Spinel ferrites MPr 0.1 Fe 1.9 O 4 (M = Mn, Cu, Mg) were prepared by sol-gel technique. X-ray Diffraction (XRD) showed that along with spinel phase, secondary phase (PrFeO 3) appeared for all composition. Scanning electron microscopy showed the inhomogeneous grain size. Temperature dependence normalized AC susceptibility and Curie temperature of spinel ferrites revealed that in all the samples transitions from multi domain (MD) to single domain (SD) occurred. Magnetic properties exhibited the soft nature of all the samples at room temperature. Temperature dependent resistivity of all the samples increased as the temperature was enhanced, representing the semiconducting behavior. Dielectric constant and complex dielectric constants were determined at the high-frequency range of 1 MHz to 3 G Hz. Impedance analysis clearly demonstrated the role of grains and grain boundary in the spinel ferrites. Cole-cole plots of all the samples showed only one semicircle at high-frequency. All the samples elaborated the good picture of Koop's theory and Maxwell-Wagner model. The low value of coercivity and high magnetization of Mn-based spinel ferrites made it suitable for hyperthermia applications.
Structural, electrical and dielectric properties of yttrium substituted nickel ferrites
Physica B-condensed Matter, 2010
In the present paper, the experimental and theoretical properties of (Sr 1 À x Ca x) MnO 3 (0 rx r 1.0) are reported. The lattice parameter and cell volume of both monoclinic [P 2 /m] and orthorhombic [Pbnm] phases of strontium calcium manganite have been calculated by using first principle calculation method. These calculated and experimental values match with each other. The dielectric constant and dielectric loss of (Sr 1 À x Ca x) MnO 3 (0 rx r 1.0) as function of frequency (20 Hz to 1 MHz) at room temperature as well as function of temperature (30-400 1C) at a frequency of 1.2 kHz are reported. This result shows the poly-dispersive nature of the system. The impedance, conductivity and electric modulus as a function of frequency have been studied.