Barium Hexaferrite Research Articles

Phase structure refinement, electric modulus spectroscopy, Urbach energy analysis, and magnetic properties of Ce3+–Ni2+-substituted Y-type barium hexaferrites

In this work, the influence of Ce3+–Ni2+ substitution on the properties of sol-gel–synthesized Y-type hexaferrites with the following chemical composition is investigated: Ba2-xCexZn0.7Co0.7Cu0.6Fe12-yNiyO22 (x = 0.0, 0.4, and 0.6; y = 0.0, 0.5, and 0.7). X-ray diffraction analysis reveals the presence of a few NiFe2O4 and Fe3O4 secondary phases in the substituted samples (M2 and M3). The Fourier-transform infrared bands at 430, 543, and 582 cm−1 are characteristic bands of iron-oxides, which indicate the vibrations of the octahedral and tetrahedral sites in the S-block of the Y-type hexaferrite. The morphology analysis reveals agglomerated grains, which were generated by weak Van der Waals force and magnetic interaction. The optical analysis reveals the presence of an Urbach energy tail. The electrical properties were investigated based on the Maxwell–Wagner two-layer model and Koop’s phenomenological theory. Increase in the magnetization is observed by substituting Fe3+ with Ni2+ and was studied according to the ligand-field theory.

Transition Metal Substituted Barium Hexaferrite-Modified Electrode: Application as Electrochemical Sensor of Acetaminophen.

This study used substituted barium hexaferrites, which were previously prepared and reported by the authors, to detect acetaminophen by the modification of a conventional glassy carbon electrode (GCE), which led to promising results. The synthesis of this electrode-modifying material was conducted using a citrate sol gel process. A test synthesis using glycerin and propylene glycol revealed that glycerin produced a better result, while less positive anodic potential values were associated with the electrooxidation of N-acetyl-p-aminophenol (NAP). Excellent electroactivity was exhibited by the cobalt-substituted barium-hexaferrite-nanomaterial-modified electrode. A good linear relationship between the concentration and the current response of acetaminophen (paracetamol) was obtained with a detection limit of (0.255 ± 0.005) µM for the Ba1.0Co1.22Fe11.41O18.11 GCE, (0.577 ± 0.007) µM for the Ba1.14Cu0.82Fe11.65O18.02 GCE, and (0.595 ± 0.008) µM for the bare GCE. The levels of NAP in a real sample of urine were quantitatively analyzed using the proposed method, with recovery ranges from 96.6% to 101.0% and 93.9% to 98.4% for the modified electrode with Cobalt-substituted barium hexaferrites (CoFM) and Copper-substituted barium hexaferrites (CuFM), respectively. These results confirm the high electrochemical activity of Ba1.0Co1.22Fe11.41O18.11 nanoparticles and thus their potential for use in the development of sensing devices for substances of pharmaceutical interest, such as acetaminophen (NAP).

Influence of particle size on magnetic and electromagnetic properties of hexaferrite synthesised by sol-gel auto combustion route

Magnetoplumbite barium hexaferrite (BaFe11.8Co0.2O19) is synthesised through sol-gel auto-combustion method under two pH conditions of precursor solutions (acidic i.e. pH < 1 and neutral i.e. pH = 7). The XRD analysis followed by Reitveld refinement indicates the formation of phase pure samples in both cases but the barium hexaferrite obtained from acidic precursor solution has smaller crystallite sizes. The Transmission Electron Microscopy (TEM) analysis followed by High Resolution Transmission Electron Microscopy (HRTEM) confirms a lower particle size of ∼20 nm for barium hexaferrite synthesised from acidic pH precursor solution. The shift in Raman peak (520-540 cm−1) by 20 cm−1, represents the whole structural block and further confirms the differences in the distribution of particle sizes due to the method of synthesis. The magnetic studies display a lower coercive field for the samples with smaller particle sizes. This is due to the crystalline size-induced microstrain that controls the magneto-crystalline anisotropy, shape anisotropy and stress anisotropy. The electromagnetic characterisation confirms broader absorption in the range of 8–18 GHz (X-band) with RL ≤ −7 db for the entire range for the samples with smaller particle sizes.

Energy band gap tuning of Ba₁˗ₓZnₓFe₁₂‐yCrʏO₁₉ doped with Cr and Zn ions to enhance the optical, dielectric, ferroelectric, and photocatalytic properties

In the current investigation, the fabrication of chromium (Cr) and zinc (Zn) doped barium hexaferrite nanoparticles (Ba₁˗ₓZnₓFe₁₂‐yCrʏO₁₉ NPs) using facile microemulsion route was undertaken. The impact of Cr and Zn doping on photocatalytic, structural, ferroelectric and dielectric properties was investigated. The X-ray diffraction (XRD) analysis revealed the formation of hexagonal ferrite structure of Ba₁˗ₓZnₓFe₁₂‐yCrʏO₁₉ NPs. The size of the NPs was in the range of 17–26 nm with tendency to form aggregates. The band gap of barium hexaferrite was increased with doping contents due to difference in ionic radii of dopants. The polarization-electric (P-E) field loops confirmed the ferroelectric behavior of synthesized Ba₁˗ₓZnₓFe₁₂‐yCrʏO₁₉ NPs. The photocatalytic activity (PCA) of Ba₁˗ₓZnₓFe₁₂‐yCrʏO₁₉ NPs was evaluated for Rhodamine B (RhB) dye removal under solar light irradiation and up to 81.8% dye degradation was observed within 90 min of irradiation. Results revealed that catalytic, ferroelectric and dielectric properties of barium hexaferrite can be enhanced with Cr and Zn doping for different applications.

Reduced graphene oxide containing barium hexaferrite composites for high frequency microwave absorption

Reduced graphene oxide containing barium hexaferrite composites for high frequency microwave absorption

A comprehensive study of structure, oxygen vacancy, and electrical properties of Mg2+ introduced in barium hexaferrite synthesized via spark plasma sintering

Barium hexaferrite BaFe12O19 (BFO) was prepared following conventional solid-state reaction procedure (CSRP) and its’ reformed compound has been prepared following CSRP and spark plasma sintering (SPS) approaches. The Rietveld refinement of synchrotron x-ray diffraction (SXRD) study assured single-phase formation of hexaferrite (M-type with space-group P63/mmc). A dense microstructure appeared in the SPS prepared sample compared to the other compounds. The presence of multiple valances of Fe (Fe2+ along with Fe3+) was studied following modified Mohr’s salt titration (MST) besides of oxygen vacancy estimation. Mg-doped increased oxygen vacancy amount via enhancing Fe2+ in the sample. As a result, the impedance was lower in the Mg-doped BFO (BFMO) samples in contrast to undoped sample, where SPS BFMO further reduced impedance.

Enhanced microwave absorption features of Ba3Co2Fe24O41 hexaferrite by high lanthanium doping concentration

AbstractControlling material structure and its electromagnetic properties, including complex permittivity and permeability, could enhance the microwave absorption performance of the material in terms of reflection loss and effective absorption bandwidth. In this study, La‐substituted barium hexaferrite, Ba3−xLaxCo2Fe24O41 (x = 0, 0.1, 0.3, and 0.5) compounds were successfully prepared using the solid‐state reaction method, and their corresponding microstructures, static magnetic properties, and electromagnetic features in 2–18 GHz were investigated. The doping of La content increased saturation magnetization, coercivity, and remnant magnetization. The Ba2.7La0.3Co2Fe24O41 epoxied sample with 3.5 mm thickness possessed an excellent microwave absorption of −47.3 dB at 3.52 GHz, and its corresponding effective absorption bandwidths were 3.75 GHz (2.25–6 GHz) and 0.57 GHz (17.43–18 GHz). It is shown that doping with various La concentrations on Ba3Co2Fe24O41 can be used as an effective technique to tune the performance of microwave absorbers based on barium hexaferrite.

Synthesis, Structure and Properties of Barium Ferrites BaFe&lt;sub&gt;11&lt;/sub&gt;M&lt;sub&gt;1&lt;/sub&gt;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.

Analysis of electromagnetic properties of Ce–Zn substituted barium hexaferrite for electronic circuit applications

Electromagnetic properties of Ce–Zn substituted barium hexaferrite (Ba0.5Ce0.5ZnFe11O19 ferrite) synthesized using ceramic technique were analyzed in detail in the X band frequencies to describe its response to microwave absorber and microwave electronic device applications. The phase formations, structural morphology, polarization mechanisms and magnetic properties for Ba0.5Ce0.5ZnFe11O19 ferrite, which provide important information about electrical load transmission mechanism were analyzed using X-ray diffraction, scanning electron microscopy, two-port vector network analyser and vibrating sample magnetometer techniques, respectively. The experimental complex dielectric plane plots (Cole-Cole plots) of the Ba0.5Ce0.5ZnFe11O19 ferrite represent an equivalent RC circuit corresponding to the impedance circuit in the Smith Chart. The reflection loss increased to the highest value (−17.04 dB) depending on the amount of Ce in the structure of the Ba0.5Ce0.5ZnFe11O19 ferrite and the bandwidth, which is important for microwave absorbers, increases.

Law of Approach to Saturation for Determining Magnetic Intrinsic Behavior of BaFe12-xMnx/2Tix/2O19 and SrFe12-xMnx/2Tix/2O19

The problem with permanent magnetic materials of very high anisotropic fields is that it is still difficult to determine the intrinsic magnetic properties, when measured using a magnetometer which has a limited magnetic field. The Law of Approach to Saturation (LAS) mathematical model provides a way to measure permanent magnets, with high anisotropic fields by correcting the magnetization data of the first quadrant curve or the virgin curve of the minor hysteresis loop. In this research, a computational LAS program was conducted to compute the intrinsic magnetic properties of magnetic materials, such as saturation magnetization, anisotropy field and magnetocrystalline anisotropy constant. Magnetization data were obtained from permagraph measurements of barium hexaferrite (BaFe12O19), strontium hexaferrite (SrFe12O19) and microwave absorbers BaFe12-xMnx/2Tix/2O19 and SrFe12-xMnx/2Tix/2O19. The convergences of magnetization were assessed to determine the effect of substitution on barium hexaferrite and strontium hexaferrite materials on saturation magnetization values, anisotropy constants and anisotropic fields.

Effect of milling duration on structural properties of polycrystalline bulk barium hexaferrite

Polycrystalline bulk Barium hexaferrite, BaFe12O19 were synthesised by ball milling for different milling duration followed by sintering at high temperature. Effect of milling duration on structural, morphological and dc electrical properties were studied for 4, 8, 12 and 16 h of milling using planetary ball mill. X-ray diffraction measurement data shows the formation of single phase barium hexaferrite which belongs to P63/mmc group for 8, 12 and 16 h milled samples. There is formation of intermediate phase along with M−phase of barium hexaferrite in 4 h milled sample. Inverse relation of the crystallite size and lattice strain was observed. The saturation value of crystallite size and maximum lattice strain were observed for 12 h milled sample. Morphological studies for 8 and 16 h milled samples reveals the formation of hexagonal plate like grains for the former and agglomerates with different grain size for the latter. High porosity for 8 h milled sample was observed by density measurements. Resistivity of the samples measured from I-V characteristics using 2 probe method exhibits maximum resistivity for 8 h milled sample and minimum resistivity for 12 h milled samples. Linear relationship was observed between electrical resistivity and porosity.

Crystal chemistry and magnetic properties of BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- hexaferrite upon heterovalent substitution of iron with zirconium

Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Messbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+-&gt;Zr4++Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x=0.6) was established. It was noted that additional sextets in the Messbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established. Keywords: M-type barium hexaferrite, heterovalent substitution, limited isomorphism, Messbauer spectroscopy, magnetic properties

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.

Кристаллохимия и магнитные свойства гексаферрита BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- при гетеровалентном замещении железа цирконием

Samples of BaFe12O19 M-type barium hexaferrite with partial iron substitution by zirconium ions (concentration up to 10 at.%) have been synthesized and investigated. Studies of crystal features, phase composition, and magnetic properties were carried out using X-ray diffraction, Mössbauer spectroscopy, and VSM respectively. The presence of limited heterovalent isomorphism by the 2Fe3+ → Zr4+ + Fe2+ mechanism was shown. The limit of heterovalent isomorphic substitution by zirconium ions in barium hexaferrite (x = 0.6) was established. It was noted that additional sextets in the Mössbauer spectra of barium hexaferrite can be formed during the localization of Zr4+ ions predominantly in the 12k and 4f2 positions due to the frustration of the magnetic structure. The correlation between the chemical composition (concentration of zirconium ions), impurity phase formation, the peculiarities of the distribution of substituents over oxygen coordination, and the magnetic properties was established.

Influence of Plasma Treatment Conditions on Structural-Phase Composition and Magnetic Properties of Barium Hexaferrite (M-type) Films on C-Sapphire

In the work investigated the influence of plasma treatment conditions on the structural-phase composition and magnetic properties of barium hexaferrite films (0001) BaFe12O19 on C-sapphire. Two treatment modes were used: with a weight average plasma temperature of 4-5 kK and 8-10 kK. It has been shown that the films obtained at the low treatment temperature have a pronounced magnetic anisotropy and saturation magnetization of 42 emu/g. The films obtained at high temperature have weak magnetic anisotropy, but have a higher saturation magnetization value of 62 emu/g. All films have low coercive fields of less than 500 Oe, which indicates the low magnetic hardness of barium hexaferrite samples and the possibility of their use as magnetic conductors of transformers, electromagnets, in measuring devices. The presented results demonstrate the promise of the plasma treatment technique in the formation of coatings with high anisotropy. Keywords: barium hexaferrite, sapphire, plasmatron, magnetization.

Microscopic Mechanism of Ferroelectric Properties in Barium Hexaferrites

Microscopic Mechanism of Ferroelectric Properties in Barium Hexaferrites

Study of dipole polarization in Zn doped barium hexaferrite

The BaFe12O19 is a ferrimagnetic ordering material, but well known as ferromagnetic material. Also, it exhibits high dielectric constant which motivate to explore the multiferroic properties in this material. Hence, researchers are interested to explore its electrical properties in the recent era. Hence, in the present report, the sol–gel prepared Zn doped barium hexaferrite has been considered to explore its electrical properties. The spontaneous polarization is observed for Zn doped barium hexaferrite. The presence of dipole polarization in barium hexaferrite could be due to presence of non-centrosymmetric P63mc (no. 186) space group. The increase in dipole polarization is observed with the increase in Zn concentration in BaFe12O19. The enhanced ferroelectric parameters like Pm, Pr and Ec are found to be 0.275 µC/cm2, 0.254 µC/cm2 and 29.0 kV/cm for BaFe11.4Zn0.6O19 sample, respectively.

Structural phase stabilization via Ba site doping with bivalent Sr, Ca and Zn ions and Fe site doping with trivalent Cr and Ga ions in the BaFe12O19 hexaferrite and its magnetic modification

Lattice structure, chemical state and magnetic properties in metal doped barium hexaferrite.

Structural and magnetic analysis of nanostructured Barium Hexaferrite

In this work, we have examined the room temperature magnetic behavior of nanostructured BaFe12O19 synthesized using sol–gel auto-combustion method. As prepared sample, have undergone through X-ray diffraction at room temperature justifying its monophase composition along with its profile well indexed for p63/mmc space group having hexagonal crystal structure. Further structural details are calculated through Rietveld refinement of XRD data thereby providing values of several structural parameters using which its crystal structure is being emphasized at VESTA software. On engineering the XRD data using Scherrer, modified Scherrer and W-H method the crystallite size was estimated to be around 60 nm. The atomic occupation and bond distribution is presented from their charge density plot based on refined structural parameters. The presence of hard magnetic phase is justified by M−H curve showing its saturation magnetization and coercivity to be 63.3 emu/g and 3642 Oe respectively under applied field of ± 20 kOe. The squareness ratio was also found to be in permissible range for uniaxial anisotropy opening path for its use in magnetic devices especially permanent magnets and data storage.

Broadband Terahertz Isolator

Breaking the reciprocity in opticalsystems is enabling the possibility of implementing devices with unidirectional wave propagation. There is currently an active search for suitable material with an efficient nonreciprocal response at the terahertz (THz) frequency range. Ideally, such a material should allow low-loss operation without an external magnetic field at room temperature. Gyrotropic hexaferrite ceramic is highly promising for achieving optical isolation in the THz spectral range. Here, we demonstrate a broadband self-biased THz isolator based on magnetized aluminum-substituted barium hexaferrite. We reveal the necessary surface density of the hexaferrite sample for the realization of THz isolation. The proposed device exhibits no less than 30 dB of isolation from 0.2 to 1 THz. Moreover, we show that the gyrotropy properties of hexaferrite ceramics can be reasonably predicted by their magnetic properties. This device is expected to be useful for applications where one-way propagation of broadband THz wave is desired.