Barium Ferrite Research Articles

Microwave Absorption and Magnetic Properties of M-Type Hexagonal Ferrite Ba0.95Ca0.05Fe12−xCoxO19 (0 ≤ X ≤ 0.4) at 1–18 GHz

In order to improve the microwave-absorption performance of barium ferrite and broaden its microwave-absorption band, BaFe12O19, Ba0.95Ca0.05Fe12O19, and Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites were synthesized by the solid-state reaction method, and the influence of Co ion substitution on the phase composition, microstructure, magnetic properties, and microwave-absorption ability of the ferrites in this system was studied. Introducing minor Co ions (x < 0.2) facilitated sintering and grain growth. At x ≥ 0.2, XRD revealed the emergence of the Co2X phase alongside the BaM phase. Increasing Co ion concentration and the secondary X-phase led to slight reductions in saturation magnetization (69 to 63.5 emu/g) and substantial decline in coercivity (2107.02 to 111.21 Oe), attributed to grain size growth and Co2X’s soft magnetic nature. Notably, Co2X incorporation significantly enhanced the microwave absorption and provided a tunable absorption band from the Ku to the C band. For a sample with a thickness of 2.0 mm and a doping level of x = 0.2, a minimum reflection loss of −59.5 dB was achieved at 8.92 GHz, with an effective absorption bandwidth of 3.31 GHz (7.07–10.38 GHz). The simple preparation method and good performance make Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites promising microwave-absorbing materials.

Electrical and EMI shielding studies of ferrite/MWCNTs/PVDF composites

AbstractIn this work, CFO/MWCNTs/PVDF and BFO/MWCNTs/PVDF composites are prepared and the comparative analysis of electrical properties and electromagnetic interference (EMI) shielding performance of both type of composites are investigated. The dielectric and conductivity characteristics are observed with varying ferrite concentration, frequency, and temperature. Ferroelectric properties are also obtained at 6 kV/cm field and EMI shielding behavior is observed in 8–12 GHz frequency range. Results exhibited that the studied properties of the composite enhances with increasing ferrite concentration that attributed to increased amount of magnetic nanoparticles. Cobalt ferrite (CFO) filled polyvinylidene fluoride (PVDF) composite is showing better properties as compared to barium ferrite (BFO) filled PVDF composites. The mechanism involve for this behavior is discussed herein.

Enhancing optical properties of Ba-Ni ferrite through nonmagnetic ion doping for sustainable green technologies and renewable energy applications

Barium ferrite powder was produced using a standard ceramic procedure, and its structure and optical properties were investigated. X-ray diffraction analysis (XRD) showed that the powder had a w-type hexagonal structure. The crystallite size was at approximately 35–36 nm, with bulk density and lattice constants increasing as zinc concentration rose. Conversely, X-ray density and porosity decreased with the increasing zinc concentration. This material has useful optical properties, as well as the standard ferrimagnetic properties of barium ferrite, which make it suitable for use in recording media. Ferrimagnetic behavior, which is useful for recording media, occurs because the powder's crystallites have their unit cell axes aligned. Up to the near-infrared part of the spectrum, the powder was found to have a very low absorption coefficient. Both of these properties—an arrangement that gives rise to ferrimagnetism and a corresponding low optical density—make barium ferrite very attractive for high-density recording and microwave applications. Fourier transform infrared spectra of the samples were recorded in the wavenumber range of 400–4000 cm−1 and supported the X-ray diffraction findings by confirming the idea of the formation of W-type hexagonal ferrite by the presence of two prominent peaks at 454 and 591 cm−1 in the FTIR spectra. Zinc addition was also found to enhance the optical properties of the material. The UV–VIS analysis confirms that the band gap energy of Ba-Ni ferrite was indeed reduced by zinc doping. Values decrease from 3.34 eV to 3.20 eV for direct transitions and from 2.96 eV to 2.79 eV for indirect transitions, using Tauc equation. That means that zinc doping enhances the optical properties of Ba ferrite without affecting the hexagonal structure of Ba-Ni ferrite. Moreover, key parameters of optical performance such as the dielectric constant, the extinction coefficient, the penetration depth, and the refractive index show a dramatic increase with a rise in zinc concentration. These attributes make zinc-doped Ba-Ni ferrite a promising optoelectronic material. The material also showed high absorbance in the wavelengths ranging from 334 to 338 nm, which makes it good for the solar cell applications. Overall, zinc-doped Ba-Ni ferrite is a good candidate for sustainable and renewable energy applications. Our study of the optical properties of barium ferrite up to the near-infrared part of the spectrum demonstrated that the powdered material has a very low absorption coefficient. Indeed, the combination of ferrimagnetism and low optical density makes barium ferrite particularly appealing for use in high-density recording and microwave technology applications.

Nanocomposite Embedded Electric and Magnetic Material Enhancing Antenna Radiation by Linear Relation in Radiators

The main and auxiliary radiating elements are linked by linear mathematical relation and coated with nanocomposite (NC) materials to enhance radiation characteristics. Nanocomposite-based electric material (NE) and nanocomposite-based magnetic material (NM) coated on auxiliary radiating elements to enhance the electromagnetic radiation of the proposed antenna. The radiating elements coated with NE graphene oxide (GO) and NM barium ferrite (BF) have higher electric field and magnetic field distribution respectively. The linear relation of main and auxiliary elements is verified by two substrates FR4, Teflon with correlated results. This proposed NC-coated antenna produces a bandwidth of 4.15 GHz, 4.02 dBi average gain and radiation efficiency of 95.17%, being superior to the antenna without NC coating. Fabricated antenna has 1.56–5.71 GHz bandwidth that includes 2.4/5.2 GHz WLAN, 2.5/3.5 GHz WiMAX, 2.4 GHz ISM, 5G SUB-6 GHz, 5G NR 78 and 2.4/5 GHz Wi-Fi bands.

Investigation of electrical, dielectric, magnetic and electrochemical characteristics of a BaFe12O19/Co0.5Zn0.5Fe2O4 nanocomposite

BaFe12O19 (barium ferrite, i.e., BaF) nanoparticles, Co0.5Zn0.5Fe2O4 (cobalt zinc ferrite, i.e, CZF) nanoparticles and their nanocomposite were synthesized for the investigation of electrical, magnetic, dielectric, and electrochemical properties. The X-ray diffraction (XRD) pattern revealed the formation of hexagonal structure for BaF nanoparticles and cubic structure for CZF nanoparticles with crystallite size of 32.44 nm and 31.30 nm, respectively. Whereas, for nanocomposite, the crystallite size obtained is 34.21 nm were shifting of peaks revealed the formation of nanocomposite. The Fourier transform Infrared (FTIR) spectra revealed the presence of metal-oxygen vibrational peaks for all the samples. The dielectric data revealed the increase in dielectric constant of nanocomposite as compared to pristine CZF whereas, loss reduced for nanocomposite significantly. Single semicircle in Nyquist plot for all the samples revealed the contribution of grain resistance in impedance. The hysteresis loop showed the increase in specific saturation magnetization from 16.963 emu/g to 21.305 emu/g for nanocomposite when compared with pristine BaF. Whereas specific remnant magnetization increased to 10.305 emu/g for nanocomposites. The electrochemical properties presented by Cyclic voltammetry showed the presence of cathodic and anodic peaks which revealed the presence of redox reaction in all samples. The specific capacitance calculated for all samples at different scan rate revealed that a nanocomposite showed highest Cs value 16.43 F/g at 25 mV, whereas it increased to 27.01 F/g, 35.93 F/g and 38.87 F/g with the increase in scan rate to 50 mV, 75 mV and 100 mV, respectively.

Effect of BaSO4 on Phase Transformation and Microstructure of CaOFe2O3TiO2 System During Sintering

The Fe2O3CaOTiO2BaSO4 system is established through miniature sintering experiments to reveal the mechanism of BaSO4 and vanadium‐titanium magnetite (VTM) with the help of X‐ray diffraction, scanning electron microscope and energy dispersive spectroscopy, and thermogravimetry. The results show that in the absence of BaSO4, the phase of the sinter consists of CaFe2O4, TiO2, Fe2O3, CaTiO3, and CaFe2O5. When the content of BaSO4 is 1% and 2%, CaTiO3 decreases and the number of needle‐like CF increases. Some Ba2+ solidly dissolve into CF and CaTiO3 to form trace BaFe12O19 and BaTi2O5. When the content of BaSO4 increases to 4%, the CaSO4 phase appears, the formation of C2F is accelerated, and the content of CF and CaTiO3 continues to decline. The needle‐like calcium ferrate gradually transforms into columnar and lamellar. As the BaSO4 content continues to increase to 6% and 8%, although the trend of each phase is similar to that at 4%, it is almost entirely composed of columnar calcium ferrite, barium ferrite, and incomplete tetragonal and rhombic Fe2O3. The results of the study provide a theoretical basis for the utilization of VTM and barium‐containing iron ores in practical production.

Bismuth oxyiodide-based composites for advanced visible-light activation of peroxymonosulfate in pharmaceutical mineralization

The presence of pharmaceutical pollutants in water bodies represents a significant environmental and public health concern, largely due to their inherent persistence and potential to induce antibiotic resistance. Advanced oxidation processes (AOPs) that employ peroxymonosulfate (PMS) activation have emerged as an effective means of degrading these contaminants. Bismuth oxyiodides (BiOI), which are known for their visible-light photocatalytic properties, demonstrate considerable potential for removal of pharmaceutical pollutants. This study examines the synthesis and performance of BiOI-based composites with barium ferrite (BFO) nanoparticles for enhanced PMS activation under visible light. BiOI and Bi5O7I were synthesized via solvothermal and electrodeposition methods, respectively, and their morphologies and crystalline structures were observed to exhibit distinctive characteristics following annealing. The formation of the composite with BFO resulted in an improvement in the catalytic properties, which in turn enhanced the surface area and availability of active sites. The objective of the photocatalytic studies was to evaluate the degradation and mineralization of tetracycline (TC) under visible light, PMS, and combined conditions. The Bi5O7I(ED)-BFO catalyst was identified as the optimal candidate, achieving up to 99.8% TC degradation and 99.4% mineralization within 90 min at room temperature. The synergistic effect of BFO in BiOI-based composites significantly enhanced performance across all conditions, indicating their potential for efficient remediation of pharmaceutical pollutant. The material's performance was further evaluated in tap water, where the degradation efficiency decreased to 56.4% and mineralization to 38.2%. These results reflect the challenges posed by complex water matrices. However, doubling the PMS concentration to 5 mM led to improved outcomes, with 93.8% degradation and 81.4% mineralization achieved. These findings demonstrate the material's robust potential for treating pharmaceutical pollutants in real-world conditions, advancing sustainable water treatment technologies.

A study on usefulness of neural network equalizer to reduce impact of amplitude fluctuations in magnetic tape

As digital data grows explosively year after year, magnetic tape devices, with their high reliability and long-term storage capacity, are widely used for backup and archiving. Magnetic tape devices with larger capacity are required, and it is necessary to improve track density. We have previously constructed a simulator that considers inter-track interference due to narrower tracks in barium ferrite (BaFe) magnetic tape drives and evaluated its performance. In this study, we develop a simulator which more accurately models the experimental data, considering amplitude fluctuations caused by the problem of poor tape running, and discuss the usefulness of a neural network equalizer to reduce the effects of amplitude fluctuations. As a result, we show that applying the neural network equalizer is useful in reducing the impact of amplitude fluctuations caused by the problem of poor tape running.

Preparation of M-type barium ferrite submicron absorbing powder by one-step high-temperature ball milling and its particle structure regulation

This study investigates a simple and rapid process for directly preparing M-type barium ferrite using high-temperature ball milling. By adjusting the rotation speed of the high-temperature ball milling, the morphology and size of the powder can be altered to regulate its electromagnetic properties, aiming for an overall good absorbing effect. The powder’s morphology, agglomeration properties, elemental valence states, and electromagnetic parameters were characterized using SEM, BET, XPS, EDS, and VNA. The results show that as the milling speed increases, the particle size of the M-type barium ferrite decreases, transitioning from the typical hexagonal flake particles to spherical block particles, forming a porous loose structure with richer dielectric loss mechanisms and enhanced electromagnetic wave loss capacity. Electromagnetic loss performance analysis indicates that at a milling speed of 50 rpm, the powder achieves the best electromagnetic loss of −61.16 dB at a matching thickness of 8.77 mm and a microwave absorption bandwidth of 4.1 GHz.

Structural, magnetic, optical, and electronic properties of vanadium-doped barium hexaferrite nanoparticles: Experimental and DFT approaches

Vanadium-doped barium hexaferrite with a nanostructure is a highly valuable material in various technological fields, such as electronics, permanent magnets, and sensors. The Ba1-xFe12-xVxO19 (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) nanoparticles derived from the aqueous solutions containing Fe:Ba molar ratio of 10:1 through the sol-gel auto-combustion method. Computational study was also performed using the first-principles density functional theory (DFT) approach. Crystal structure optimization, band structure, and density of states (DOS) calculations were conducted by CASTEP code. The variation of the structural, magnetic, optical, morphological, and electronic properties of V5+-doped barium hexaferrite was investigated. The XRD analysis combined with the Rietveld refinement showed the hexagonal structure of M-type barium ferrite (BaM), confirmed by the FT-IR analysis. The morphology of BaM nanoparticles was studied by the FE-SEM and TEM micrographs. In addition, magnetic and optical properties were analyzed through VSM and UV–Vis analysis. Crystallite size was found to be highly effective in tuning the coercivity and optical band gap of barium hexaferrites, which varied, respectively, from 3.24 to 4.83 kOe, and 2.69–3.69 eV. Magnetic results showed that several variables like cations distribution, lattice strain, and hematite secondary phase affected the nanoparticles’ magnetization. The DFT simulation results showed a sharp reduction of electronic band gap energy whether V takes the position of Ba or Fe (from 1.10 eV in undoped to 0.64 and 0.14 eV in doped structures). The projected density of states (PDOS) calculations demonstrated that the d orbitals of V and Ba mainly contribute to the valence band maximum (VBM) and conduction band minimum (CBM), respectively.

Unlocking the power of Zn-substituted barium ferrite (BaFe2O4) nanoparticles for unprecedented magnetic, dielectric, and optical enhancement for photovoltaic devices

Unlocking the power of Zn-substituted barium ferrite (BaFe2O4) nanoparticles for unprecedented magnetic, dielectric, and optical enhancement for photovoltaic devices

Optimal formulation and performance evaluation of functional ultra-high performance concrete with barium ferrite

The employment of a core catcher is instrumental in enhancing the safety of nuclear power facilities in the event of severe accidents, with sacrificial materials serving as fundamental constituents. Currently, cement-based sacrificial materials are prevalently utilized due to their straightforward construction methodologies and economical production costs. These materials are designed to withstand significant impact loads arising from the descent of core melt during severe accidents. To augment the impact resilience of sacrificial materials, a novel functional ultra-high performance concrete (FUHPC) incorporating barium ferrite has been developed. Using the Modified Andreasen and Andersen particle packing model to determine the initial mixture of FUHPC, and the impact of barium ferrite on the mechanical and thermal properties of FUHPC was systematically evaluated. Furthermore, the influence of barium ferrite on the FUHPC's microstructure was examined with mercury intrusion porosity and scanning electron microscopy techniques. The findings indicate: (1) Optimal barium ferrite incorporation led to a decrease in the porosity and the threshold pore diameter of FUHPC; (2) The flexural and compressive strengths, as well as the elastic modulus of FUHPC, were found to increase within the ranges of 4.41%–17.50 %, 2.88%–22.91 %, and 5.80%–15.06 %, respectively, as a result of suitable barium ferrite additions; (3) At a barium ferrite concentration of 2 vol%, the chloride migration coefficient of FUHPC was reduced by 21.43 %; (4) The presence of barium ferrite enhanced the impact performance of FUHPC, with a 21.38 % increase in impact resistance noted at a barium ferrite content of 2 vol%; (5) In high-temperature scenarios, the formation of channels from melted polypropylene fibers served to mitigate the spalling of FUHPC; (6) Upon considering the effects of barium ferrite on both room temperature and elevated temperature performance, as well as on microstructural characteristics, the optimal barium ferrite content was determined to be 2 vol%.

Highly crystalline oriented BaScFe11O19 with low FMR linewidth

Hexaferrites with strong magnetocrystalline anisotropy have potential applications in the self-biased planar microwave devices. Using a simple high temperature sintering strategy, highly c-axis crystalline orientation has been obtained in the barium ferrites. Compared with polycrystalline BaScFe11O19 sintered at a temperature of 1040 °C, the sample sintered at the higher temperature of 1330 °C has a much larger crystallite size (∼100 μm) and higher relative density (ρR=97.78%), with a much narrower ferromagnetic resonance linewidth (ΔH=322Oe).

Synergistically enhanced electromagnetic absorption in barium ferrite/hollow carbon spheres/epoxy composites

The ongoing technological advancements have emphasized the importance of absorbent coatings, which are essential for effectively absorbing electromagnetic waves across various industries, including electronics, healthcare, and security systems. In this research, barium ferrite particles and hollow spherical carbon particles have been synthesized to investigate the synergistic effect of different compounds in absorbing electromagnetic waves in the epoxy coating. The barium ferrite particles were synthesized in two distinctive rod and spherical morphologies at 600 and 900 °C, employing the sol-gel technique. Also, hollow spherical carbon particles were synthesized. Synthesized particles were analyzed structurally and chemically with an X-ray Powder Diffraction, Fourier infrared spectrometer, vibrating‐sample magnetometer, field emission Scanning Electron, and Raman spectroscopy.The absorption characteristics of a coating that contains rod and spherical morphologies of barium ferrite and hollow spherical carbon particles can be adjusted by controlling the amounts of synthetic compounds in the 8–12 GHz range. The results indicate that combining rod-shaped barium ferrite particles (900 °C) and hollow spherical carbon particles in a thin epoxy coating improves impedance matching and wave attenuation. Notably, when the epoxy coating is 1.5–2 mm thick and contains 20 % rod-shaped barium ferrite particles (900 °C) and 1 % hollow spherical carbon particles, reflection loss values of < -20 dB are observed at frequencies of 10–12 GHz.

Improved EMI Shielding Behavior of Barium Ferrite Coated Carbon Fibers in Low‐Density Polyethylene Composites with an Optimized Electroless Coating Process

AbstractThis study describes using carbon fibers coated with magnetic material as a filler in polyethylene for EMI shielding. It investigates how to utilize barium ferrite (BaFeO3) as a conducting filler in a polyethylene matrix by optimizing the conditions for its electroless deposition onto carbon fibers. Various polymer nanocomposite samples were prepared using varying concentrations of BFO@CF. Scanning electron microscopy is used to assess the surface appearance of the composite and the distribution of BFO@CF within the polymer matrix. Including MWCNT/graphene nanoplatelets exhibit superior shielding properties, and the polymer composite with the BFO@CF demonstrates enhanced mechanical properties. The 8.2 to 12.4 GHz frequency range is used to study the EMI shielding properties. For the composition ratio of LDPE: MWCNT: GNP: BFO@CF (50 : 5 : 47.5 : 2.5), a maximum shielding of 67 dB was attained. After BFO@CF was added to the matrix, the absorption mechanism rather than the reflection mechanism dominated the shielding mechanism. A thorough evaluation and discussion of the shielding mechanism and parameters are presented.

Phase Separation of ϵ‐Fe2O3 and BaFe12O19 in a Synthesis Combining Reverse‐Micelle and Sol‐Gel Techniques

AbstractEpsilon iron oxide (ϵ‐Fe2O3) and magnetoplumbite barium ferrite (BaFe12O19) are well‐known hard ferrites. For one synthesis method of ϵ‐Fe2O3, combining reverse‐micelle and sol‐gel techniques, Ba ions are used to accelerate the formation of nanorod‐shaped ϵ‐Fe2O3. On the other hand, in synthesis of BaFe12O19 both Ba and Fe ions are used to form the final product. However, the coexistence of these two ferrites has not been reported by any synthesis. Herein, we investigated the effect of Ba ions on the final product for the synthesis combining reverse‐micelle and sol‐gel techniques. At a low Ba ion ratio of [Ba]/[Fe]=0.2, ϵ‐Fe2O3 nanorods are formed, while at higher Ba ion ratios ([Ba]/[Fe]=0.4, 1, 2), BaFe12O19 appears. The phase diagram at 1000 °C shows that at a Ba ion ratio of [Ba]/[Fe]=1, the ratio of ϵ‐Fe2O3 and BaFe12O19 is almost 1 : 1. The diagram shows intermediates between these two phases do not form, indicating a phase separation of ϵ‐Fe2O3 and BaFe12O19. During the sintering process of this synthesis, initially perovskite‐type Ba2Fe2O5 and γ‐Fe2O3 nanoparticles form. Then, in areas where γ‐Fe2O3 nanoparticles are gathered around Ba2Fe2O5 and react, BaFe12O19 is formed, whereas in areas lacking Ba2Fe2O5, ϵ‐Fe2O3 nanorods are formed within Ba‐ion containing silica glass.

Investigating Enhanced Microwave Absorption of CNTs@Nd0.15-BaM/PE Plate via Low-Temperature Sintering and High-Energy Ball Milling.

Composite plates comprising a blend of rare earth neodymium-(Nd) doped M-type barium ferrite (BaM) with CNTs (carbon nanotubes) and polyethylene WERE synthesized through a self-propagating reaction and hot-pressing treatment. The plates' microscopic characteristics were analyzed utilizing X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), thermo-gravimetric analysis (TGA), Raman, and scanning electron microscopy (SEM) analytical techniques. Their microwave absorption performance within the frequency range of 8.2 to 18 GHz was assessed using a vector network analyzer. It showed that CNTs formed a conductive network on the surface of the Nd-BaM absorber, significantly enhancing absorption performance and widening the absorption bandwidth. Furthermore, dielectric polarization relaxation was investigated using the Debye theory, analyzing the Cole-Cole semicircle. It was observed that the sample exhibiting the best absorbing performance displayed the most semicircles, indicating that the dielectric polarization relaxation phenomenon can increase the dielectric relaxation loss of the sample. These findings provide valuable data support for the lightweight preparation of BaM-based absorbing materials.

Broadband absorptive metamaterials enhanced by magnetic rubber to broaden bandwidth

A method to extend the operational bandwidth of metal-dielectric-metal (MDM) type absorptive metamaterials is proposed. An ultrathin, five-band absorptive metamaterial with wide-angle absorption and polarization sensitivity in the X-band is designed. The total absorption bandwidth across the five bands, with reflection losses below −10 dB (absorption rate greater than 90 %), is nearly 1 GHz. The physical mechanisms of absorption are analyzed through the distributions of surface current, electric field, and magnetic field. Samples were fabricated and tested, and the results were consistent with the simulation outcomes. To enhance the bandwidth of the absorptive metamaterial and its application prospects, magnetic materials such as barium ferrite and carbonyl iron were introduced into a rubber vulcanization layer, which was then combined with the ultrathin absorptive material to create a novel absorptive material. When the magnetic material content in the rubber layer was 50 wt%, the frequency range with reflection losses below −10 dB increased by approximately nine times, covering 69.5 % of the C-Ku band. This significantly broadens the bandwidth of the pure MDM-type absorptive metamaterial, providing a feasible solution for the design of broadband ultrathin absorptive materials.

Innovative approach for trace level detection of mefenamic acid by ferrite nanocomposite-based electrochemical sensor

In the present work, the rapid and highly efficient catalyst has been designed for the electrochemical sensing of the non-steroidal drug Mefenamic acid (MFA) for quality control and clinical assessment. Ferrite nanocomposite (SFBF-NC) has been synthesized by sol-gel method from the precursor sodium ferrite and barium ferrite and applied for the electrochemical sensing of MFA. The SFBF-NC was examined by various analytical methods to confirm its coral-like shape with a highly rough and porous structure, cubic/spinal phase crystallinity, and average crystalline size < 60 nm with good stable electronic properties. Due to the large electroactive surface area, fast electron transfer rate, and potent electrocatalytic activity of SFBF-NC, the fabricated SFBF-NC/GCE showed good sensitivity for the quantitative determination of MFA. The proposed sensor showed the limit of detection (LOD) of 2.12 nM with a linear range of 0.01–450 μM for MFA detection. Additionally, the proposed sensor demonstrated excellent catalytic activity, stability, repeatability, and selectivity for MFA sensing and was utilized for the routine analysis of MFA in biological and pharmaceutical samples.

Crystal structure, microstructure, and magnetic properties of Ba3-xNdxCo2Fe24O41 hexaferrite ceramics with enhanced magnetic anisotropy

Crystal structure, microstructure, static and dynamic magnetic properties of Ba3-xNdxCo2Fe24O41 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were investigated. Samples were prepared via sintering at 1250 °C for 4 h, and XRD results revealed their crystal structure after Nd substitution. With the increase in Nd3+ ion dopant content, particle porosity increased, leading to slight decrease in volume density. Static magnetic data showed the weak effect of Nd-substitution on saturation magnetization strength and a slight increase in coercivity (from 52 Oe to 75 Oe at x = 0–0.5), while out-of-plane magnetic anisotropy rose significantly (from 10.1 kOe to 14.5 kOe at x = 0–0.5). Dynamic magnetic tests demonstrated noticeable decrease in permeability (from 17 to 8), whereas cutoff frequency increased from 0.8 GHz to 1.9 GHz and the maximum Snoek product reached 18.8 GHz for the sample with x = 0.4. The fitting of real part of permeability using domain wall resonance and natural resonance models revealed that resonance frequency and out-of-plane anisotropy both increased with Nd-substitution. Moreover, despite Nd doping, samples maintained low magnetic loss and high Q value within higher frequency range. Therefore, findings of this study provide a pathway to development of substituted Z-type barium (Co2Z) ferrites for high frequency applications.