Barium Hexaferrite Research Articles

Study on the Faraday rotation angle of La-substituted barium hexaferrite in the terahertz band.

M-type barium hexaferrites (Ba1-xLaxFe12O19) were prepared by the liquid phase epitaxial (LPE) method, in which Ba2+ was substituted by La3+. The Faraday rotation effect of materials in the frequency range of 0.5-0.8 terahertz (THz) is studied by THz time-domain spectroscopy (THz-TDS). It was demonstrated that the M-type barium hexaferrites have a large Faraday rotation angle, and the Faraday rotation angle can be further enhanced by the substitution of La3+. For 500 µm thick film samples, the Faraday rotation angle exceeded 20° under the maximum measuring magnetic field of 400 mT. Moreover, the Faraday rotation angle is not saturated, and it will further increase with the increase of the magnetic field. At 0.8 THz, the Faraday rotation angle of the sample with x = 0 is 21.48°, for x = 0.05 which is 21.62°, and for x = 0.19 which is 28.38°. The Faraday rotation angle is enhanced by about 32%. By measuring the magnetic properties of the material, we found that the fundamental cause of the enhancement in the Faraday rotation angle lies in the increased saturation magnetization of the material after La3+ substitution. In the experiment, it was also found that the transmittance of the material to the THz wave decreased sharply with the increase of La substitution. For sample x = 0, the transmittance is as high as 60%. When the substitution amount of La is only x = 0.05, the transmittance decreases to about 55%. When the maximum substitution amount of La is x = 0.24, the transmittance of the material is only about 2%.

Strong magnetoelectric coupling in novel Na0.5Bi0.5TiO3–BaFe12-2xCoxTixO19 multiferroic composite

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) and Co–Ti substituted Barium Hexaferrite (BaFe12-2xCoxTixO19; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63/mmc hexagonal phases corresponding to Na0.5Bi0.5TiO3 and BaFe12-2xCoxTixO19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x≠0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future.

Design of magnetic elastomer composites with tunable magnetic responses from soft to hard magnetization

Magnetic elastomer composites with tunable magnetic responses from soft to hard magnetization have been synthesized. Co-Ti co-doped barium hexaferrite (BaCoxTixFe12–2xO19) nanopowders were used as the filling and polydimethylsiloxane (PDMS) as the matrix. The effects of magnetic field-induced alignment of BaM magnetic particles in the matrix on the properties of the prepared composites have been investigated. For anisotropic magnetic elastomers, the formed chain structure plays a positive role in the enhancement of the shear energy storage modulus of the elastomers. The enhanced energy storage modulus is increased by about 190 % compared with that of the isotropic magnetic elastomers. Due to the magnetic chain structure of the magnetic particles and its effect on the rubber molecular chain, the anisotropic magnetic elastomers can obtain higher magnetic deformation response capability in the direction of the parallel magnetic field. Their research lays a foundation for further designing tunable magnetic flexible sensors.

Magnetic Barium Hexaferrite Nanoparticles with Tunable Coercivity as Potential Magnetic Heating Agents.

Using magnetic nanoparticles (MNPs) for extracorporeal heating applications results in higher field strength and, therefore, particles of higher coercivity can be used, compared to intracorporeal applications. In this study, we report the synthesis and characterization of barium hexa-ferrite (BaFe12O19) nanoparticles as potential particles for magnetic heating. Using a precipitation method followed by high-temperature calcination, we first studied the influence of varied synthesis parameters on the particles' properties. Second, the iron-to-barium ratio (Fe/Ba = r) was varied between 2 and 12. Vibrating sample magnetometry, scanning electron microscopy and X-ray diffraction were used for characterization. A considerable influence of the calcination temperature (Tcal) was found on the resulting magnetic properties, with a decrease in coercivity (HC) from values above 370 kA/m for Tcal = 800-1000 °C to HC = 45-70 kA/m for Tcal = 1200 °C. We attribute this drop in HC mainly to the formation of entirely multi-domain particles at high Tcal. For the varying Fe/Ba ratios, increasing amounts of BaFe2O4 as an additional phase were detected by XRD in the small r (barium surplus) samples, lowering the particles' magnetization. A decrease in HC was found in the increased r samples. Crystal size ranged from 47 nm to 240 nm and large agglomerates were seen in SEM images. The reported particles, due to their controllable coercivity, can be a candidate for extracorporeal heating applications in the biomedical or biotechnological field.

Synthesis, thermal X-ray, neutron diffraction, Mössbauer spectroscopy and magnetic properties investigation of Al doped barium hexaferrite BaFe11AlO19

Polycrystalline aluminum substituted barium hexaferrite BaFe11AlO19 synthesized by the ceramic technique. The results of energy dispersive X-ray analysis, thermal X-ray diffraction (XRD), neutron diffraction, Mössbauer spectroscopy, magnet properties measurements were measured. XRD analysis demonstrated P63/mmc hexagonal structure of BaFe11AlO19. The magnetic sublattice of barium hexaferrite BaFe11AlO19 was obtained using neutron diffraction data. The distribution of aluminum in barium hexaferrite matrix at positions 2a and 12k was obtained with Mössbauer spectroscopy. A comparison of the calculated intensities of the neutronograms and the actual ones allowed us to establish that in position 2a the aluminum ion occupied a position with the coordinate (1;1;0), and the position of the substituent ion in position 12k (0.83333; 0.66667; 0.10810). According to neutron diffraction data, it was found that the actual Curie temperature is lower than that measured by differential scanning calorimetry.

Influence of the Substitution of Iron by Aluminum and Titanium on the Structure and Properties of Barium Hexaferrite

Influence of the Substitution of Iron by Aluminum and Titanium on the Structure and Properties of Barium Hexaferrite

Investigation of photocatalytic degradation of diclofenac sodium and acetaminophen by Zn-Ag co-doped barium hexaferrite@CNTs Composite

Herein, a facile coprecipitation route was followed to synthesize Zn-Ag co-doped barium hexaferrite (ABHF) and its nanocomposite with carbon nanotubes (CNTs) using the ultrasonication method. Various characterization techniques were used to analyze the structure and optical properties. The bandgap energy of BHF and ABHF was 2.16 eV, and 2.09 eV respectively. Diclofenac sodium and acetaminophen were used to study the photocatalytic activity of the synthesized samples. It was noted that the bare sample showed 29.46 % and 44.96 % degradation for diclofenac sodium and acetaminophen respectively. The highest catalytic activity was shown by the nanocomposite (ABHF@CNTs) that degraded 70.87 % and 84.34 % of diclofenac sodium and acetaminophen respectively. Photodegradation of diclofenac sodium and acetaminophen (pharmaceutical drugs) was increased due to a reduction in bandgap energy (Eg), increased surface area, and prolonged e--h+ pair recombination of the synthesized samples.

High frequency enhancement of dielectric constant, crystal structure analysis, and magnetic properties of Pr3+- Zn2+ substituted Co2Y-type barium hexagonal ferrites

The effect of Pr3+-Zn2+ doping on the magnetic and dielectric properties of Co2Y-type barium hexaferrites with the chemical composition Ba2Co2Fe12-x-yPrxZnyO22 (x = 0.00, 0.10, 0.20, and y = 0.00, 0.15, 0.25), was investigated in this study. The prepared Pr3+-Zn2+ substituted Co2Y-type barium hexaferrites were calcined for 5 h at 1100 °C in a digital heating chamber. The XRD analysis confirms the presence of a crystalline phase in the undoped Co2Y-type barium hexaferrite samples, with a space group identified as R-3m. Characteristic absorption bands of Co2Y-type barium hexaferrites were observed at 540 and 422 cm−1 due to the asymmetric stretching vibration of Fe3+ and O2− at both, octahedral and as well as tetrahedral crystallographic sites. The magnetic interaction between the particles causes slight agglomeration. Dielectric and impedance spectroscopy were performed using Koop's phenomenological theory and the Maxwell-Wagner two-layer dielectric relaxation model. The ε′ was found to decrease with an increase in applied frequency due to the space-charge polarization phenomenon. The rise in ε′ at higher frequencies enhances the material's suitability for high-frequency applications. The magnetic parameters were extracted from the M − H hysteresis loop, and it was observed that they were affected by the site preferences of Pr3+ and Zn2+. The prepared Y-type hexaferrite's optimized magnetic parameters make it a good option for magnetic memory applications.

Optimization of magnetic properties: Investigating the interaction of synthesis temperature, particle size, and monodomain formation in barium hexaferrite synthesized by the Pechini method

This study presents the synthesis and characterization of barium hexaferrite (BaFe12O19) powders via the Pechini method, employing controlled pH conditions (pH = 1) followed by sintering at temperatures ranging from 800 °C to 1150 °C. Structural and magnetic properties of the samples were investigated using various techniques, including Vibrating Sample Magnetometry, X-ray Diffractometry, and Scanning Electron Microscopy. Additionally,a theoretical analysis was conducted to determine the critical size required for achieving a single magnetic domain in the material. The results reveal a correlation between synthesis temperature and crystal size, ranging from 76 nm (at 800 °C) to 632 nm (at 1150 °C). Notably, samples sintered at 1050 °C exhibited exceptional magnetic properties, displaying a saturation magnetization (Ms) of 75.1 emu/g, a remanent magnetization (Mr) of 36.7 emu/g, and a coercivity (Hc) of 5.65 kOe. The particle size of these samples measured 327 nm, closely aligning with the critical diameter calculated for barium hexaferrite (378 nm) in this study. This optimal critical size was identified in sample sintered at 1050 °C, resulting in notably high coercivity values compared to those reported in previous literature. These findings highlight the significance of synthesis temperature control in tailoring the magnetic properties of barium hexaferrite, offering insights into optimizing its performance for various applications.

Mean-field model for BaFe[formula omitted]Ti[formula omitted]O19 ([formula omitted] 0 and 0.2) hexaferrite: Structural and magnetic properties

An experimental and theoretical investigation of the magnetic properties of Ti-doped barium hexaferrite (BaM) is conducted. Polycrystalline samples of BaFe12−xTixO19 with x≤ 0.2 were synthesized using the solid-state reaction method. X-ray diffraction (XRD) analyses, along with Rietveld refinement, confirmed the presence of BaFe12O19 as the predominant BaM phase and a minor amount of hematite in all samples. Structural analysis revealed a slight increase in lattice parameters a and c for x=0.2. A result mostly related to the preferential occupation of Ti4+ ions at the 4f2 and 12k sites, coupled with the reduction of Fe3＋ ions to Fe2＋. It was also found that the magnetic response of samples is affected by Ti4+ substitution. Saturation magnetization slightly decreased from ∼ 45 (x= 0) to ∼ 44 emu/g (x= 0.2), the anisotropy constant from ∼4.08× 105 to ∼4.06× 105 erg/g2, while coercivity slightly increased from ∼ 2456 to ∼ 2468 Oe, and the anisotropy field from ∼ 18.2 to ∼ 18.6 kOe. The magnetic features of the samples were analyzed in terms of a proposed model based on the mean-field theory. Results indicated that the substitution of Ti4+ ions resulted in a decrease in the magnetic moment of the 2b sublattice. Such behavior is influenced by its closest neighboring sites 12k and 4f2 sublattices, which are the preferred occupancy sites for the Ti4+ cations.

Electromagnetic interference shielding and DFT study of barium hexaferrites nanoparticles coated polyaniline with heterointerface polarization behavior

Barium-hexaferrite-nanoparticles (BHNs) and polyaniline-nanoparticles (PNs) were prepared individually with average particle sizes of 50 nm and 42 nm. The two nanoparticles were then combined to create hybrid nanoparticles (HNs) with a ferritic core and a conductive surface, by chemically coating polyaniline onto the surface of BHNs via in-situ polymerization. The nanoparticle shape, size, structural, and morphological properties were analyzed using SEM, XRD, and PSA. The nanoparticles were dispersed into a PVDF matrix to produce nanocomposite-films (NFs) for testing EMI shielding effectiveness. The NFs exhibited excellent blocking of near infrared radiation and a shielding effectiveness of more than 50 dB in the microwave region when 30 wt% of HNs was used in the PVDF matrix. Density-function-theory (DFT) based on first-principle was used to confirm the interfacial polarization contribution at the heterointerface, revealing different electron occupied states and considerable charge transfer and accumulation at the interface, enhancing the EMI shielding effectiveness.

Evaluation of structural characteristics BaFe(12-x)InxO19 hexaferrite compounds at high temperatures

BaFeO-based hexaferrite compounds were synthesized by partially replacing Fe atoms with In atoms in barium hexaferrite, and their structural characteristics, thermal, and magnetic properties were studied. The crystal structure and lattice parameters of the hexaferrite were investigated using the X-ray diffraction method. Thermal property investigations were conducted at high temperatures. The results obtained by the Differential Scanning Calorimetry (DSC) method were analyzed, and the mechanisms of formation and decomposition of hydroxide groups in these crystals were explained. These effects were also determined by Thermogravimetric Analysis (TGA) studies. The vibrational magnetometry method studied the magnetic properties of BaFe11.4In0.6O19 and BaFe10.8In1.2O19 compounds. As the concentration of In atoms in the samples increases, the temperature of the ferrimagnetic-paramagnetic phase transition decreases. The observed effect in the temperature range of RT to 800 °C is attributed to weight loss due to the decomposition of structural water molecules through an endothermic reaction in hexaferrite compounds. The value of the Curie temperature for the BaFe11.4In0.6O19 compound was 383 °C, and for the BaFe10.8 In1.2O19 compound, it was 323 °C. Increasing In concentration from x = 0.6 to x = 1.2 increases the In3+ ionic radius in the structure, and due to the replacement of Fe3+ ions with more In3+ ions at x = 1.2, the magnetic hyperfine field area decreases.

Tuning Dynamic Susceptibility in Barium Hexaferrite Core–Shell Nanoparticles through Size-Dependent Resonance Modes

Tuning Dynamic Susceptibility in Barium Hexaferrite Core–Shell Nanoparticles through Size-Dependent Resonance Modes

An analysis of iron ion occupation in barium hexaferrites prepared employing different synthesis techniques from magnetic and Mossbauer studies

An analysis of iron ion occupation in barium hexaferrites prepared employing different synthesis techniques from magnetic and Mossbauer studies

Structural, physicochemical and electrical properties of Co2Y-type barium hexaferrites

Y-type hexaferrite ceramic materials of nominal composition Ba2Co2CrxYxFe12-2xO22 (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were synthesized by sol-gel auto combustion route. Y-type hexaferrites are technologically important ceramic materials for fabricating modern electronic devices and microwave absorbers due to their unique electrical and dielectric properties and reflection loss behavior. XRD classifies the single-phase formations with space group R 3‾ m. The crystallite size of the synthesized samples was calculated in (34–41) nm range. The specific absorption band in FTIR spectra approves the (Fe–O) stretching vibrations at wavenumbers 446 and 478 cm−1. The substitution of iron by Cr3+ and Y3+ increases DC resistivity from 1.03 × 1011 to 1.17 × 1012 Ω cm by limiting the electrons jumping between ferrous and ferric ions. The activation energy and drift mobility were also calculated among the substituting content of Cr3+-Y3+. The dielectric response in 1 MHz–6 GHz frequency was determined and the effect of substitution has been observed. The Maxwell-Wagner (MW) bilayer model is used to study dispersion in dielectric parameters with reference to applied frequency. The maximum values of dielectric losses were obtained at 6 GHz in the range of 0.37–0.60. The coercivity values confirms the soft magnetic nature of synthesized samples. The microwave absorption (MW) properties of synthesized materials were improved upon Cr3+-Y3+ substitution. Minimum reflection loss RLmin = −66 dB (99.99% absorption of MW) at 1.46 GHz frequency and 1.96 mm thickness was obtained for x = 0.09 composition. All investigated samples are efficient materials for stealth technology, radar cross-reduction, EM interference shielding, and high-frequency applications.

A New Method for Analysis of Martials Nano and Micro Electronics Technologies

This final qualifying work investigates prospective microelectronic and nano electronic materials. The purpose of the final qualifying mission is to evaluate potential manufacturing technologies and materials. In the first phase of the endeavor, potential materials for microelectronics and nanoelectronics were investigated. Graphene, fullerenes, fullerites, carbon nanotubes (CNT), nanofibers, ferrites, barium hexaferrite, nano powders, and epitaxial coatings are among these substances. An investigation into diverse methodologies pertaining to the production of auspicious materials was undertaken during the preliminary stage of the undertaking. Molecular beam epitaxy, pulsed laser deposition, spray deposition, physical vapor deposition (PVD), chemical solution deposition, gas-phase synthesis, electrospinning, chemosynthesis, detonation synthesis and electric explosion, chemical vapor deposition (CVD), spray deposition, physical vapor deposition (PVD), and the sol-gel method were among these processes.

Synthesis and Characterization of Barium Hexagonal Ferrite (BaFe12O19)

Barium Ferrites is a good class of electrical material due to its high resistivity. It is mainly used in electronics and telecommunication industry due to their novel electrical properties. We have synthesized barium hexagonal ferrite (BaFe12O19) by solid state reaction method. The prepared precursor was calcined at temperature 750°C and characterized by FTIR, XRD and SEM. X-ray diffraction analysis confirmed the single-phase formation of BaFe12O19. Using the Debye Scherrer formula, the crystallite size of BaFe12O19 was calculated, and the average particle sizes were 26.52 nm, 27.17 nm, 19.17 nm and 23.67 nm. The result confirms that barium ferrite powder has a constant size of less than 30 nm. Four peaks at 2θ values of 35.52, 43.22, 57.21 and 62.84 degrees, corresponding to (110) (111) (210) and (211) planes of Barium ferrite have been observed. The FTIR spectra showed important signature absorption spectra of hexaferrite at 314 cm−1, 499 cm−1 & 628 cm−1. These peaks confirm the formation of barium hexaferrites. The SEM images of barium hexaferrite at 750°C showed large number of vertically grown barium hexaferrite nanorods with a grain size between 110 nm to 130 nm. Thus, barium ferrite is a good candidate in the use of electronics and communication sector.

Improved magnetoelectric coupling of Co–Ti substituted barium hexaferrite at room temperature and related electrical investigations

This paper reports a systematic study of the electrical, multiferroic and magnetoelectric coupling properties of Co–Ti substituted Barium hexaferrites, having the chemical composition BaFe12-2xCoxTixO19 (x = 0–2.0; in steps of 0.5), synthesized using the sol gel auto-combustion method. X-ray Diffraction (XRD) studies and Rietveld refinement confirmed the successful incorporation of Co–Ti ions in the hexaferrite lattice with all the samples displaying Pb63/mmc space group single phase structure. Scanning Electron Microscope (SEM) images revealed the inhibition of crystal growth in a particular direction with Co–Ti substitution. The conduction mechanisms of the samples were analysed from the conductivity measurements and were found to follow Jonschers power law. The complex impedance spectroscopy analysis and the Cole-Cole plot fitted diagrams of the samples indicated the enhancement of bulk resistivity and grain boundary resistivity with substitution. Saturation magnetizations of the substituted samples decreased and were ascribed to the replacement of Fe ions by Co–Ti ions at different crystallographic sites. The observed reduction in anisotropy constant indicated the disturbance in the magnetic axis. The multiferroic nature of the substituted samples at room temperature was confirmed from the soft ferroelectric loops. Room temperature magnetoelectric coupling coefficient was found to be largely enhanced with substitution, achieving an exceptionally high value of 182mV/cmOe for the x = 1.5 sample. This may prove useful for potential use in emerging device applications as a single phase room temperature multiferroic material.

THE EFFECT OF BARIUM SUBSTITUTION WITH COMBINATIONS OF RARE EARTH ON PERMANENT MAGNETIC SURFACE MORPHOLOGY BASED ON BARIUM HEXAFERRITE

The development of hard magnets today is progressing very rapidly. Developing hard magnets based on rare earth metals becomes a severe problem when the raw materials are not readily available. The chosen solution is to replace oxide-based permanent magnets with small amounts of rare earth metals substituted to improve their magnetic properties. This study synthesized a permanent magnet oxide based on barium hexaferrite doped with lanthanum and cerium atoms. In the synthesis of this material, a mechanical wet milling technique is used to obtain a single-phase permanent magnetic Ba1-β-γLaβCeγFe12O19 system with composition (β = 0 - 0.5 and γ = 0 - 0.1). The precursors are weighted according to their stoichiometric composition. Each mixed composition was milled by high energy milling (PW 1000 in the mixer/mill) at a milling speed of 1000 rpm using steel balls with an average diameter of 12 mm. Grinding conditions included a ball-to-powder weight ratio of 2:1, milling time 5 hours, then compacted with 7000 Psi pressure and sintered at 1200oC for 2 hours. The surface morphology and microstructure of the resulting sample particles were observed using scanning electron microscopy (SEM) with the SEM JEOL JED 305 brand. The characterization results show that the particles are hexagonally homogeneous in shape with particle sizes in the range of 1000-2000 nm for β = 0 and γ = 0 (without doping). In general, the four samples with varying concentrations of doping ions La3+ and Ce4+ showed homogeneous hexagonal structures but smaller particle sizes than pure barium hexaferrite. The sample particle sizes ranged from 500-1000 nm for β = 0.02 and 300-1000 nm for β = 0.04.

Study of phase transition temperature in defect-induced barium hexaferrite

Sol-gel auto combustion method has been used to synthesize M−type barium hexagonal ferrite (BaFe12O19). The defects were created in M−type BaFe12O19 utilizing the 15UD Pelletron tandem accelerator. The synthesized BaFe12O19 was exposed to 200 MeV Ag16+ ions radiation, and the shift in the phase transition of M−type BaFe12O19 were explored through in-situ ultrasonic measurement. The defect-induced sample exhibits reduced magnetization compared to the pristine ferrite, attributed to ion-induced disorder and a decline in superexchange interactions. Further, the defect-induced sample experiences a decrease in coercivity owing to reduced crystallite and grain sizes caused by irradiation. The phase transition temperature shifts from 732 K in the pristine sample to 540 K in the defect-induced sample.