Structure Of Barium Hexaferrite Research Articles

Effect of sintering temperature on the structural, morphological, optical and electrical properties of Ba1 − xLaxFe12O19

La substituted M-type Barium hexaferrite, Ba(1−x)La(x)Fe12O19, (x = 0.25 and 0.30) were synthesized using ball milling followed by heat treatment at 1150˚C and 1300˚C and the influence of sintering temperature as well as La doping were presented. X-ray diffraction, FESEM, dielectric spectroscopy, and ferroelectric measurements were performed to study the structural, morphological, dielectric, and ferroelectric properties of the prepared samples. Rietveld refinement on the X-ray diffraction measurement reveals the formation of a phase magnetoplumbite structure of barium hexaferrite only for the samples sintered at 1300˚C. The secondary phase, along with the major magnetoplumbite structure, was observed for the sample sintered at 1150˚C. Hexagonal plate-like grains of different sizes were observed, and samples sintered at 1300˚C showed large-size grains. Porosity was observed to decrease with La doping. Impedance spectroscopy reveals that Maxwell-Wagner-type polarisation occurs with the relaxation of mobile charges having long-range hopping. However, the ferroelectric property was suppressed for samples sintered at 1300˚C.

Synthesis BaFe12O19/RGO Composite As Microwave Absorber For Ku-Band

In this study, a composite microwave absorber consist of barium hexaferrite (BaFe12O19) and Reduced Graphene Oxide (RGO) for Ku-band (12-18 GHz) was prosperous blend. Barium hexaferrite to arrange using the sonochemical method and at calcination temperature of 1000°C and a holding time of 1 hour. Subsequently, commercial RGO was composited with barium hexaferrite at a weight percentage of 6% RGO. The synthesized composite was characterized using X-Ray Diffraction (XRD) to analyze the formed phases, Raman Spectroscopy to confirm the presence of RGO in the composite, and Vector Network Analyzer (VNA) to evaluate the microwave absorption performance. The XRD test results show that there is no change in the crystal structure of barium hexaferrite due to the addition of RGO. The VNA test results showed that the addition of RGO could enhance the reflection loss value of barium hexaferrite. The BaFe12O19/RGO compound displayed a reflection loss value of -14.43 dB at a frequence of 16.50 GHz.

Mn-doped BaFe12O19 nanoparticles synthesis via micro-emulsion route: Solar light-driven photo-catalytic degradation of CV, MG and RhB dyes and antibacterial activity

A pristine and Mn-doped BaMnxFe12-xO19 (x =0.0–0.3) NMs were synthesized via a facile micro-emulsion route. The impact of substitution was assessed across various properties including structure, ferroelectric behavior, dielectric characteristics, photocatalytic performance, and antibacterial activity. X-ray diffraction analysis confirmed the presence of a single-phase hexagonal structure of barium hexaferrite (BHF). The P-E analysis revealed the high coercivity, Remnant polarization and maximum polarization of doped materials versus pure BaFe12O19. Doping led to a reduction in the energy bandgap, consistent with the observed increase in polarization. The photocatalytic activity (PCA) of pure BaFe12O19 (BHF) was compared with highly substituted BaMn0.3Fe12O19 (BMHF5) for the degradation of Crystal Violet, Malachite Green and Rhodamine B dyes under visible light irradiation. The doped BMHF5 exhibited superior PCA (94.6, 92.2 and 96.5 (%) for CV, MG and RhB dyes, respectively). The doped material also showed promising antibacterial activity. Owing to the promising enhanced optical properties, BMHF5 has the potential for the treatment of wastewater under solar light irradiation.

Investigations on structural, Mossbauer, dielectric, and ferroelectric properties of La doped barium hexaferrite

La substituted Barium hexaferrite, Ba(1-x)La(x)Fe12O19, (x = 0, 0.1, 0.15, 0.20) was synthesized using ball milling followed by heat treatment. Rietveld analysis of X-Ray diffraction patterns reveals the formation of a single-phase magnetoplumbite structure of barium hexaferrite for all prepared samples. Morphological studies using FESEM shows the formation of hexagonal plate-like grains with different grain size, and the average grain size decreases with La doping. Elemental analysis using EDS confirms that the observed elemental composition for all the samples is within the expected range within the experimental error. Density measurements observed that porosity decreases up to La content x = 0.15 and then slightly increases for x = 0.20. Mössbauer spectroscopy studies reveal no formation of Fe2+ ions but delocalization of electrons after La doping. There is not much variation in the hyperfine structure with La doping. It is observed from the dielectric spectroscopy that the highest dielectric constant and low loss are observed for La content x = 0.20. The P-E loop of the pristine sample shows small polarisation but leaky behavior, whereas La substitution shows both leaky and resistor circuit-type behavior but large polarization.

Effect of La substitution on the structural and chemical properties of Barium hexaferrite via Mossbauer spectroscopy

M-type Barium hexaferrite is a famous hard magnetic material with a hexagonal crystal structure. La substituted Barium hexaferrite, Ba(1-x)La(x)Fe12O19, (where, x = 0.25 and 0.30) were synthesized using ball milling followed by sintering at 1300 °C for 5 hours. X-ray diffraction patterns reveal the formation of a single-phase magnetoplumbite structure of barium hexaferrite, which belongs to the P63/mmc space group. Mossbauer spectroscopic studies were carried out to study the magnetic phase, the effect of La doping on the valency of the Fe atom, and charge distribution in the prepared samples. Mossbauer spectra is fitted using 5 sextets, shows there is 5 sublattices present in the system. From the fitting of Mossbauer spectrum, it is observed that, there is no formation of Fe2+ ion even if the doping levels are as high as 30%, as it is expected that Fe3+ ion changes its valance to maintain the charge neutrality. However, there is an increase in s-electron density for number of sites with doping. Quadrupole splitting values shows spherical charge distribution for all the sublattices except 2b, due to asymmetric nature of bipyramidal site. Slightly varied magnetic hyperfine splitting values are observed for 12 k and 4f1 sites shows the effect of La substitution.

Synthesis, Structure and Properties of Barium Ferrites BaFe<sub>11</sub>M<sub>1</sub>O19 (M= Al, Ti and Mn) Ceramics

The article shows the results of a research in which barium hexaferrite samples of the BaFe11M1O19 (M= Al, Ti and Mn) composition were obtained by solid-state synthesis. Samples substituted with titanium, aluminum, and manganese were obtained in a tubular furnace at an exposure time of 5 hours at a temperature of 1350°C, the sample, substituted with manganese, it was obtained at a temperature of 1250°C. The chemical composition was controlled using electron microscopy the samples obtained correspond to the initial composition with sufficient accuracy. Hexagonal plates represent the structure of all the obtained samples. According to X-ray phase analysis, all samples are monophasic and have the structure of barium hexaferrite. Using the data of powder X-rays, the parameters of the unit cell of the studied samples were calculated, when iron atoms are substituted by titanium or aluminum or manganese atoms, the crystal lattice is distorted, while its change is not the same for different crystallographic directions. During the doping of barium hexaferrite with titanium, aluminum or manganese atoms, the Curie temperature decreases. This is due to a decrease in the exchange interaction forces during the modification of the barium hexaferrite matrix. The aim of this study was to study the structure and change of the lattice parameters, the Curie temperature, depending on the substitution element.

Влияние замещения железа алюминием и титаном в гексаферрите бария BaFe(12–2x)TixAlxO19 на структуру и свойства

The study of ferrites is currently one of the most important directions in scientific field, which is confirmed by a large number of publications on this topic. Ferrites are promising mate-rials to be used in high-frequency electronics. The ferrite with the structure of magnetoplumbite is the most promising for the needs of microwave electronics, namely, barium hexaferrite BaFe12O19, as well as solid solutions based on it. The substitution of iron atoms in the structure of barium hexaferrite by other elements such as aluminum or titanium leads to significant changes in physical properties such as magnetic permeability, saturation magnetization, coercive force, Curie temperature, ferromagnetic resonance frequency, electrical conductivity. Thus, understanding how each of the iron-substituting elements affects the physical properties of a solid solution based on barium hexaferrite gives us the opportunity to smoothly adjust the characteristics of ferrite for a specific engineering task. The present paper studies the effect of the substitution of iron in the structure of barium hexaferrite by the aluminum and titanium atoms upon the change in parameters of the crystal lattice and physical properties. Monophase samples based on barium hexa¬ferrite of the BaFe12O19, BaFe11AlO19, BaFe11TiO19, and BaFe11Al0.5Ti0.5O19 compositions were obtained by the solid-phase synthesis. The degree of substitution of iron by aluminum or titanium, as well as joint substitution by aluminum and titanium was the same for all samples. The resulting samples were studied by X-ray diffractometry, electron microscopy, and differential scanning calorimetry. According to the X-ray diffraction analysis data, the patterns of changes in parameters of the crystal lattice were revealed following the atom substitution. The Curie temperature for all the studied samples was measured by the method of differential scanning calorimetry. Conclusions are drawn about the influence of the substituting element on the Curie temperature value.

EVOLUTION OF FERRO ELECTRIC AND FERRO MAGNETIC PROPERTIES OF RARE EARTH ALUMINIUM SUBSTITUTED M-TYPE BARIUM HEXA FERRITES AT ROOM TEMPERATURE

The ferro-electric and ferro-magnetic properties of rare earth aluminium substituted Mtype barium hexa-ferrites with the composition of BaAlxFe(12-x)O19 where (x=0.2, 0.4, 0.6, 0.8, 1.0 and 1.2) have been prepared by oxides as precursors employing powder metallurgy route. The structural properties, functional groups, 3-D visualization, elemental analysis, surface morphology, magnetic, optical properties and ferro electric properties of the prepared samples have been characterized through X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR), diamond visualization software, Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM), UV-Visible spectroscopy (UV-VIS) and ZT-IA measurement system respectively. The structural measurements depict the confirmation of M-type barium hexa-ferrite structure. EDS spectrum illustrate the elemental composition of the prepared materials for every corresponding ‘x’ values. The surface morphology shows the existence of platelet like intergranular pores. Magnetic measurements shows that the saturation magnetization (Ms) decreases and coercivity (Hc) increases with increasing aluminium contents. The optical band gap energy increases as the crystallite size decreases. The variation of electric polarization has also been occurred due to the shifting of iron ions in the unit cell structure of oxygen octahedron FeO6.

Comparison between centrosymmetric and non-centrosymmetric chromium substituted M-type barium hexaferrites

In this research project a series of chromium substituted barium hexa-ferrites with formula BaCrxFe(12-x)O19 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) have been synthesized using powder metallurgy route, sintered at 1100 °C for 2 h. The structural, functional analysis, surface morphology, magnetic and ferroelectric properties have been investigated using X-ray diffractometer, Fourier infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and ferroelectric technique, respectively. The structural analysis reveals the formation of barium hexaferrite structure with minor secondary phase of Hematite α- Fe2O3 in first five samples. Surface morphology shows that all grains have definite grains shape and grain boundaries. VSM analysis revealed the antiferromagnetic loops due to existence of hematite phase in (x = 0 to x = 0.5) samples, whereas the sample (x = 0.6) shows the ferro-magnetic behavior. Ferroelectric measurement shows centrosymmetric and non-centrosymmetric orientation and maximum remnant polarization due to presence of more Fe2+ ions in (x = 0.1–0.5) so that not proper closing of first five samples enhanced the magnetoelectric (ME) coupling.

Correlation between the Chemical Composition, Crystal Structure, and Magnetic Properties of Hexagonal Barium Ferrite with Zn2+ Heterovalent Substitution

This paper presents a detailed study of the magnetic and crystal structures of BaFe12 –xZnxO19 (0.25 ≤ x ≤ 1.5) Zn-substituted barium hexaferrite by Mossbauer spectroscopy, vibrating sample magnetometry, and X-ray diffraction. Partial heterovalent substitution of Zn2+ ions for Fe3+ ions demonstrates limited heterovalent isomorphism according to the scheme 2Fe3+ → Zn2+ + Fe4+, which satisfies the electroneutrality constraint. Mossbauer spectroscopy results indicate the presence of Fe4+ in the BaFe12 –xZnxO19 materials. The heterovalent isomorphous substitution limit has been determined to be x = 1.0. The formation of a zinc spinel has been shown to begin at x = 0.50 and its content increases with increasing zinc content. Data are presented on the predominant character of the substituent ion (Zn2+) distribution in the structure of barium hexaferrite. A correlation has been found between the chemical composition, phase separation, anisotropy of properties, and the temperature of the magnetic phase transition of BaFe12 –xZnxO19 (0.25 ≤ x ≤ 1.5).

Effect of High-Energy Ball Milling on Molten Salt Synthesized Barium Hexaferrite Powder

M-type hexagonal ferrite powder was prepared by the molten salt flux method calcined at a relatively low temperature (850 °C) with a product yield of 99.87%. The synthesized sample was then milled for 3 h by high-energy ball milling in toluene suspension to obtain ultrafine nanoparticles. The structural, morphological, and magnetic properties of the particles were investigated to observe the effect of milling on the molten salt synthesized powder. The analyses reveal the presence of barium hexaferrite (BaFe12O19) as the main phase with less impurities. Average crystallite size, determined by X-ray diffraction (XRD), decreased from 81 ± 20 nm to 52 ± 5 nm after ball milling. The Fourier transform infrared (FTIR) spectra ensure the tetrahedral and octahedral positions in barium hexaferrite structure with an increase in the intensity of absorption bands after milling. The electron paramagnetic resonance (EPR) signal shows a broad line that demonstrates a decrease in the amplitude of the milled sample. Furthermore, remanence measured by vibrating sample magnetometer (VSM) increases from 8.5 to 25 emu/g. A 72% increase in coercivity and 84% increase in magnetic saturation is observed for the milled samples compared to that of pure BaFe12O19 (unmilled). The variations of the magnetic properties are thus attributed to the reduction in crystalline size and lattice parameters after milling.

Исследование особенностей состава, магнитной и кристаллической структуры гексаферрита бария BaFe-=SUB=-12-x-=/SUB=-Ti-=SUB=-x-=/SUB=-O-=SUB=-19-=/SUB=-

The results of studies of the composition, crystal, and magnetic structure of Ti-substituted barium hexaferrite BaFe12 - xTixO19 (0.25<x<1.5) by Mössbauer spectroscopy, vibration magnetometry, X-ray diffraction, and synchronous thermal analysis are presented. Partial substitution of Fe3 + ions by Ti4 + ions revealed the presence of a limited heterovalent isomorphism realized according to the 2Fe3+ = Ti4+ + Fe2+ while maintaining charge balance. Using Mössbauer spectroscopy, an increase in the electron density of 3d electrons and the presence of Fe2+ in BaFe12 - xTixO19 samples with x = 1.5 were established. The limit of heterovalent isomorphic substitution is established, which is in the range 0.75 <x <1.0. Using Mössbauer spectroscopy and X-ray diffraction, the formation of titanium-containing phases at x = 1, 0, the content of which increases with increasing degree of substitution, is shown. Information is provided on the predominant distribution of substituent ions (Ti4+) in the structure of barium hexaferrite at positions 12k and 2b.

Rare earth ion contribution in barium hexaferrite structure to a change of magnetocrystalline anisotropy to improving its magnetic properties

Rare earth ion contribution in barium hexaferrite structure to a change of magneto-crystalline anisotropy to improving its magnetic properties has been investigated. A series of simples of Ba1-xCexFe12O19 with the variation of x (x = 0.0-0.5) were prepared by solid-state reactions using mechanical deformation techniques. The oxide materials used for sample preparation are BaCO3, Fe2O3, and CeO2 with the ratio of material used is adjusted to the stoichiometric calculation for variations of Ce4+ substitution. The phase identification results show that the reaction took place perfectly and successfully formed a single-phase Ba1-xCexFe12O19 namely at the composition x = 0 and x = 0.1. while for the composition x> 0.1, it is formed in three phases. Particle morphology in the composition x = 0 and x = 0.1 has very good and uniform particle homogeneity across the surface of the sample in the form of polygonal particles. So the substitution of Ce atoms into the barium hexaferrite structure is only able at the composition limit x = 0.1. In the composition x = 0.1 has been able to increase the coercivity and magnetization fields. It can be concluded that the permanent magnet with the composition Ba0,9Ce0.1F12O19 gives the best results.

Magnetic and microwave absorption properties of barium hexaferrite doped with La3+ and Gd3+

In this paper, BaLa‌xGdxFe12-2xO19 (x=0.2, 0.4, 0.6 and 0.8) were synthesized via sol-gel auto-combustion method. Fourier transform infrared spectroscopy (FTIR) of samples was represented that the bands at 400 and 500 cm-1 were related to the formation of hexaferrite phase. The (x-ray diffraction) XRD patterns were matched exactly with the structure of barium hexaferrite. (Field emission scanning electron microscopy) FESEM were represented the hexagonal shapes of all products. Magnetic analysis of barium hexaferrite were investigated by (vibrating sample magnetometer) VSM. The saturation magnetization of all samples decreased by increasing dopant’s substitution due to the different occupation sites of dopants instead of Fe3+ (64 to 36.56 emu/g) in the hexaferrite structure. The coercivity increased because of its reverse relation with saturation magnetization (5010 to 5500 Oe). Microwave absorption properties of samples was investigated by (vector network analyzer) VNA. The maximum value of reflection loss was -7.8 db at 10.4 GHz frequency in 3mm thickness for x=0.4 sample.

Study of the structural, magnetic, and microwave absorption properties of the simultaneous substitution of several cations in the barium hexaferrite structure

In this research study, multi dopant barium hexaferrites nanoparticles with nominal composition of BaCoxCuxZr2xFe12-4xO19 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by sol-gel auto-combustion method. Then, their magnetic and microwave properties were studied in detail. These characteristics were investigated using various instruments including X-ray diffraction (XRD) by the FULLPROF program, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). The XRD, along with FTIR evaluations confirmed the successful substitution of Co, Cu and Zr cations in the barium hexaferrite lattice. The VSM analysis proved that by increasing cobalt, copper and zirconium substitutions, the saturation magnetization, coercivity and remanence values are decreased. With an increase in the concentration of Co-Cu-Zr ions, a monotonic decrease in coercivity, ranging from 3540 Oe to 396 Oe was also observed. The reasons of the changes in the magnetic and microwave absorption properties by adding the multi dopant were also investigated. The maximum reflection loss of −27.4 dB observed in BaCo0.5Cu0.5ZrFe10O19 sample with a bandwidth of about 5.3 GHz which covered almost whole measured microwave frequency range of 12–18 GHz. Which make it to be a good candidate to design single layer microwave absorber for applying in the Ku band.

Enhancement of structural and magnetic properties of M-type hexaferrite permanent magnet based on synthesis temperature

The main purpose of this research work is to develop the single domain magnetic particles of M-type barium hexaferrite (BaFe12O19) using oxide precursors employing conventional powder metallurgy technique. The phase formation and magnetic performance of the powders and magnets will be optimized by adjusting calcination and sintering temperatures. The synthesis of M-type barium hexaferrite was carried out in two sections. A series of four samples have been prepared by initial wet mixed powders calcined at different temperatures, i.e., 750, 850, 950 and 1050 °C. On the basis of structural analysis, the sample calcined at 950 °C has been selected and further divided into four parts to sintered them at 1100, 1150, 1200 and 1250 °C. The structural measurements depict the confirmation of M-type barium hexaferrite structure. SEM micrographs show the hexagonal-shaped grains. The abrupt decrease in coercivity for the sample sintered at 1250 °C has been seen which may be due to high sintering temperature, at which the particles have multi-domain properties.

Barium ferrite prepared by modified Pechini method: effects of chloride and nitrate counter ions on microstructures and magnetic properties

Barium hexaferrite powders were successfully prepared by the modified Pechini method using citrate and glycerol. The materials were prepared employing different Ba:Fe ratios, iron(III) precursors and calcination temperatures. The obtained powders were characterized by XRD, VSM, SEM, EDX and FT-IR. The Ba:Fe molar ratio of 1:11, for both chloride and nitrate series, is observed to be the optimal ratio to attain the phase-pure barium hexaferrite. Moreover, these barium hexaferrite powders synthesized with the Ba:Fe ratio of 1:11 showed the highest saturation magnetization among the samples in the same series. Interestingly, the powders formed from chloride precursors had significantly lower coercive fields than those from nitrate precursors, highlighting the role of counter ions. The reasons were likely to be the smaller particle sizes in materials obtained from the nitrate precursors and possibly the distortion of the barium hexaferrite structure due to the substitution of some oxide with the chloride species within the materials obtained in the chloride series.

Mechanism for Synthesizing Barium Hexagonal Ferrite by Sol-Gel Method

A new mechanism has been proposed for synthesizing barium ferrite by sol-gel method. The mechanism takes account of the structure of barium hexaferrite and the least structure change principle. It is useful in optimizing the synthetic conditions.

Collapse of the Magnetic Hyperfine Structure of Barium Hexaferrite by Mechanochemical Activation

The collapse of the magnetic hyperfine structure of barium hexaferrite as an effect of mechanochemical activation was investigated. The various inequivalent sites and phases present in the milled material were studied by transmission Mossbauer spectroscopy. Barium hexaferrite nanoparticles were obtained after only 2 h of milling time and were found to coexist with iron oxide particles for longer times of exposure to mechanochemical activation. The milled samples were then subjected to thermal annealing, in order to test the reversibility of the collapse of the hyperfine structure. The thermal annealing performed (700°C, 1 h) was partly successful in restoring the magnetic hyperfine structure of milled hexaferrite. Complementary information was obtained using transmission electron microscopy (TEM) and electron diffraction (ED).

Effect of bismuth oxide on the phase composition and magnetic properties of the 12Fe2O3 � 3BaO � 2CoO system

A study was made of the effect of the addition of the low-melting-point bismuth oxide on the phase composition and magnetic properties of the 12Fe2O3·3BaO·CoO system. The optimum Bi2O3 concentration, at which the key magnetic properties attain their maxima, is 1 wt.%. The influence exerted by bismuth oxide on the magnetic properties of the ferrite is associated with qualitative and quantitative changes in the phase composition and microstructure of specimens and possibly also with partial dissolution of the barium hexaferrite structure.