Ferrite BaFe12O19 Research Articles

4D printing of the ferrite permanent magnet BaFe12O19 and its intelligent shape memory effect

4D printing of the barium ferrite permanent magnets provides new opportunities for intelligent structure and process innovation of permanent magnets. In this paper, the preparation, filament manufacture, and intelligent printing methods with shape memory/recovery effect are studied for the barium ferrite permanent magnet. Firstly, the PLA/TPU/BaFe12O19 composite materials are developed by adding different contents of ferrite permanent magnet BaFe12O19 powders into the PLA/TPU (polylactic acid/thermoplastic polyurethane) matrix. The weight percentage of the BaFe12O19 is 10–40 wt% with an interval of 10 wt%. Secondly, the composites are pelletized and further extruded to manufacture composite filaments with different BaFe12O19 contents. Scanning electron microscope (SEM) is used for the microstructural analysis. The BaFe12O19 particles are uniformly distributed in the PLA/TPU matrix, and the slight particle agglomeration phenomenon occurs in the composite filaments with 30 and 40 wt% BaFe12O19. The thermal properties of PLA/TPU/BaFe12O19 composite filaments are analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). After adding the barium ferrite particles, the glass transition temperature of the composite filaments changes within a small range from 53.5 °C to 55 °C. Thirdly, the filaments are successfully manufactured to magnet parts by the fused deposition modeling (FDM) 3D printing for the tests of mechanical, magnetic, and shape recovery properties. With the increase of the barium ferrite content, the magnetic properties show a rising trend, proving the feasibility of using 3D printing technology to make magnets. The shape memory effects of the printed parts are excellent and the shape recovery ratios show a rising trend, from 85.6 % to 88.9 % under heat contact stimulus and from 88.9 % to 97.8 % under electromagnetic induction non-contact stimulus. Relatively, the parts hold fast response speed due to direct contact with the heat source under the heat stimulus, and the parts hold higher shape recovery ratios due to more heats produced under the electromagnetic induction stimulus. The addition of magnetic particles is helpful to improve the heat transfer ability and provide the possibility of non-contact heat transfer. The magnetic parts with complex structure and intelligent shape memory/recovery effect can be achieved for special application requirements. As a result, the research of this paper expands preparation methods of new magnetic composite materials, explores the manufacture process for intelligent magnets and lays a solid foundation for the development of new permanent magnet devices.

Electrospun PVDF/Barium hexaferrite fiber composites for enhanced electromagnetic shielding in the X-band range

In the contemporary, digitally–driven era, the prevalence of electronic devices has drastically escalated electromagnetic (EM) pollution levels, marking a significant environmental challenge. Electrospun fiber composites of polyvinylidene fluoride (PVDF) and Barium hexaferrite (BHF) were analyzed for their potential usage in X-band electromagnetic shielding applications (EMSAs). Pure PVDF and BHF-PVDF fiber composite were manufactured by needleless electrospinning. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and EM measurements utilizing a vector network analyzer (VNA) are all used to describe the prepared samples. The XRD and FTIR analyses confirmed the successful incorporation of BHF into the PVDF matrix. The results show that adding PVDF to BHF in fiber form enhances the reflection loss (RL), indicating improved electromagnetic shielding effectiveness (EMSE). The SEM analysis revealed that the fiber composite had a uniform fiber diameter distribution. In contrast, the TGA analysis demonstrated good thermal stability of the fiber composite. Polymer samples were evaluated to enhance gamma radiation and neutron particle attenuation. MCNP5 and Phy-X/PSD software were used to study semi-crystalline fluorocarbon polymer (PVDF) and barium hex ferrite BaFe12O19 (30 wt%) with PVDF (70 wt%). The MCNP5 programme simulated 0.015–15 MeV radiation attenuation. Additionally, the Phy-X/PSD programme verified the simulated µ values for the chosen Mxenes materials. The MCNP-5 code and Phy-X/PSD results were agreed. The linear attenuation coefficients for the polymer samples ranged from 3.166 to 0.032 cm2.g−1 for PVDF and from 73.960 to 0.113 cm2.g−1 for PVDF and BHF-PVDF Fiber at photon energies from 0.015 to 15 MeV. Overall, the electrospun fiber composite of PVDF and BHF particles shows promise for EMSAs in the X-band range. The enhanced RL observed in our study suggests that these fiber composites could be used to protect against electromagnetic radiation (EMR) from electronic devices, which is increasingly concerning in today's modern society.

Effect of the Fe/Ba and Fe/Sr ratios on the phase composition, dielectric properties and magnetic characteristics of M-type hexaferrites prepared by the hydrothermal method

Powders of BaFe12O19 and SrFe12O19 ferrites are synthesized by hydrothermal method from iron, strontium, and barium nitrates. The ratio of iron and barium (strontium) cations in the precursor solution was varied to establish the optimal conditions for the maximum yield of hexaferrite. X-ray diffraction, Mössbauer spectroscopy, vibrating sample magnetometry and dielectric spectroscopy are used for the characterization of the obtained materials. At a high Fe/Ba (Fe/Sr) ratio, the powders contain α-Fe2O3 as a secondary phase, which significantly reduces the magnetization and slightly decrease the coercivity. At the same time, a low Fe/Ba (Fe/Sr) ratio leads to the formation of BaFe2O4 (SrFeO3-x), which also leads to a decrease in magnetization and a sharp drop in the coercivity. Powders with a high content of hexaferrite are characterized by excellent coercive force (>5 ​kOe) and can be considered as a material for permanent magnets.

Structural and magnetic properties of a BaFe12O19/NiFe2O4 nanostructured composite depending on different particle size ratios

A nanostructured magnetic composite based on hexagonal ferrite BaFe12O19 (magnetically hard) and cubic ferrite NiFe2O4 (magnetically soft) is synthesized. The hexagonal ferrite precursor is obtained by the Sol-Gel method using citric acid as a coordinating agent. The precursor obtained is heated at different temperatures to get nanoparticles with different sizes. Cubic ferrite is obtained by chemical co-precipitation, method and the nanoparticle growth process is controlled with different heat treatments. The hexagonal and cubic ferrite nanoparticles are mixed providing low energy. Three samples of this kind of composite are obtained with a different ratio of particle size. The composites are a mixture where there are clusters of the minority phase NiFe2O4 distributed in a matrix of the main phase BaFe12O19. Both ferrite phases are composed of nanoparticles with an average size less than 50 nm without tensions in the crystal lattice. These structural parameters were compared between the composites and their precursor ferrites. The relationship between the composite microstructures and their magnetic properties is analyzed. A weak exchange coupling was detected between the component magnetic phases of the composites. Depending on the synthesis conditions, some samples exhibit monodomain or a multidomain regime. The higher BH product appears for composites from ferrites with a nanoparticle size ratio approximately equal to one. The structural characterization is carried out by X-ray diffraction. The homogeneity of the composition in the volume of the nanostructured composites is analyzed with a field emission scanning electron microscope equipped with energy dispersive spectroscopy for the analysis of the element mapping. The magnetic study is carried out through measurements of magnetization as a function of the applied field (M vs. H) at 300 K.

In-situ measurement of mineral phase transition and kinetics in roasting process of Bayan Obo mixed rare earth concentrate by sodium carbonate

In this study, the Bayan Obo rare earth concentrates mixed with Na2CO3 were used for roasting research. The phase change process of each firing stage was analyzed. The kinetic mechanism model of the continuous heating process was calculated. This study aims to recover valuable elements and optimize the production process to provide a certain theoretical basis. Using X-ray diffraction (XRD), Fourier infrared spectroscopy, scanning electron microscopy with energy dispersive spectrometry, the reaction process and the existence of mineral phases were analyzed. The variable temperature XRD and thermogravimetric method were used to calculate the roasting kinetics. The phase transition results show that carbonate-like substances first decompose into fine mineral particles, and CaO, MgO, and SiO2 react to form silicates, causing hardening. Further, REPO4 and NaF can directly generate CeF3 and CeF4 at high temperatures, and a part of CeF4 and NaF forms a solid solution substance Na3CeF7. Rare earth oxides calcined at a high temperature of 750 °C were separated to produce Ce0.6Nd0.4O1.8, Ce4O7, and LaPrO3+x. Then, BaSO4, Na2CO3, and Fe2O3 react to form barium ferrite BaFe12O19; the kinetic calculation results show that during the continuous heating process, the apparent activation energy E reaches the minimum in the entire reaction stage in the temperature range of 440–524 °C, and the reaction order n reaches the maximum, which indicates that the decomposition product REFO significantly impacts the reaction system and reduces the activation energy. The mechanism function is F(α) = [−ln (1−α)]1/3. The reaction order n reaches the minimum in the temperature range of 680–757 °C, and the apparent activation energy E is large. The difficulty of the reaction increases during the final stage. The reaction mechanism function is F(α) = [1−(1−α)1/3]2. Observing the entire reaction stage, the step of controlling the reaction rate changes from random nucleation to three-dimensional diffusion (spherical symmetry).

Effect of Reaction Time on the Coercivity of Barium Ferrite Synthesized by Hydrothermal Process

The barium ferrite BaFe12O19 with c-plane anisotropy, which possessed relative high saturation magnetization and low coercivity, had been synthesized by hydrothermal method with different reaction time of 5 h, 8 h,11 h,14 h, and 17 h. The X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM) were used to study the phase composition, microstructure and magnetic properties of barium ferrite, respectively. The results showed the intensities of the peak were enhanced and there was no impurity phase. With the prolonging of the reaction time to 11 h, 14 h and 17 h, the grain size increased, and the equivalent diameter was about 1 μm, and the thickness was about 100 nm. When the reaction time was 17 h，the coercivity of barium ferrite was 1104 Oe. The reduction of coercivity was ascribed to the increase of particle size and the reduction in magnetic anisotropy.

Exchange spring behaviour in BaFe12O19/CoFe2O4 magnetic nanocomposites

Abstract In this work, nanopowders of BaFe12O19 and CoFe2O4 and nanocomposites of (1−x) BaFe12O19/xCoFe2O4, for x = 0.00, 0.25, 0.50, 0.75 and 1.00, were prepared via co-precipitation and high-speed ball milling techniques, respectively. For structural analysis, the X-ray diffraction revealed the formation of hexagonal BaFe12O19 and spinel CoFe2O4 ferrites, and the average crystallite sizes were about 35 nm and 15 nm, respectively. The transmission electron microscope indicated that the two phases are well distributed and the grain sizes of the composite powders are verified employing the size distribution histograms where two peaks were obtained separately for both ferrites. From EDX spectra, it was shown that all samples exhibit an excellent compositional homogeneity verifying the presence of both phases in the obtained nanocomposite powders. Magnetic measurements were performed via a vibrating sample magnetometer at 300 K and 77 K. The results showed a good single-phase magnetic behavior, proving the good exchange coupling between hard and soft phases. For low CoFe2O4 content, the dipolar interactions were dominated by the exchange-coupling interactions. Additionally, the optimum values of saturation and remanent magnetizations as well as the squareness ratio were obtained for the x = 0.5. This was attributed to the dominance of exchange-coupling interaction. Magnetic properties for nanocomposites were improved as the temperature falls from room temperature down to 77 K. This increase is skilled to the reduction in the thermal fluxes of magnetic moments at the surface.

Synthesis and characterization of BaFe12O19-CoFe2O4 ferrite composite for high-frequency antenna application

Recently, ferrite composite ceramics have received much attention for high-frequency device applications as the composite has both dielectric and magnetic properties, good chemical stability, and high electrical resistivity. M-type hexagonal ferrite BaFe12O19 (BaM) and cubic spinel ferrite CoFe2O4 (CoF) composites; (BaM)1−x(CoF)x (x = 0.0, 0.25, 0.50, 0.75, and 1.0) were successfully synthesized by co-precipitation method. X-ray diffraction (XRD) analysis confirmed the formation of pure-phase BaM ferrite at 800 °C and CoF ferrite at 600 °C, respectively. The XRD analysis of composite ferrite showed the presence of both BaM and CoF ferrite phases in the composite. The composites were sintered at 1100 °C/4 h. The composite with x = 0.25 composition showed the most compact microstructure structure and higher bulk density compared to other composites. The composite (with x = 0.25) also showed the highest permittivity (~ 15), permeability (~ 13), and antenna miniaturization factor (~ 14) at 500 MHz due to mainly better densification. The permeability of composite was almost stable up to about 500 MHz. The coercivity was lowest in the composite with x = 0.25 composition indicating a change of hard magnetic behavior of BaM ferrite into a soft magnetic character after composite formation, which may be due to the formation of enlarged grain of BaM in the composite.

Microwave absorbing characteristics in multilayer absorbers based on barium ferrite and teflon

In order to investigate a new microwave absorbing characteristics of multilayer absorbers. Barium ferrite BaFe12O19 was synthesized by a standard ceramic method. Teflon was obtained from the china product and is available in the market. Multilayer absorbers based on 2 mm of barium ferrite layer thickness and 0.5 mm of teflon layer thickness with 2, 4, 6 and 10 layers were characterized by using vector network analyzer (VNA) Rohde-Schwarz ZVA 67 for 7.5 – 11.5 GHz frequencies. Reflection loss (RL) of multilayer absorbers were calculated and simulated using the transmit line theory. The microwave absorption abilities were enhanced for multilayer structure due to the combination of barium ferrite and teflon layers. The optimal absorption ability was achieved with − 20 dB (i.e. 99.9 % absorption) of reflection loss.

Peculiarities of the Crystal Structure and Texture of Isotropic and Anisotropic Polycrystalline Hexagonal Ferrites BaFe12O19 Synthesized by Radiation-Thermal Sintering

In this work the crystal structure and texture of isotropic and anisotropic polycrystalline hexagonal ferrites BaFe12O19 obtained by the method of radiation-thermal sintering (RTS) is studied using X-ray diffraction and X-ray phase analysis. Crude blanks of both isotropic and anisotropic hexaferrites are obtained by the standard method of ceramic technology from the same raw material (Fe2O3 and BaCO3 of the analytical grade brand) and on the same equipment with the only difference being that the anisotropic blanks were pressed in the magnetic field H = 10 kOe. For sintering raw billets, a linear electron accelerator ILU-6 (electron energy Ee = 2.5 MeV) is used (Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences). The samples are sintered in air for one hour at 1200, 1250, 1300, and 1350°C. It is shown for the first time that high-quality single-phase isotropic and anisotropic hexaferrites BaFe12O19 can be obtained from raw blanks of a ferritized charge using the RTS technology. The properties of the crystal structure and texture of the obtained objects of the research are described. It is established for the first time that the dependence of the pref.orient.o1 predominant orientation of the crystal texture parameter on the degree of the magnetic texture f in polycrystalline hexagonal barium ferrites of type M is described by the expression pref.orient.o1 = –0.005f + 0.6886.

Microwave absorption in 0.1–18 GHz, magnetic and structural properties of SrFe12-xRuxO19 and BaFe12-xRuxO19

The hexagonal SrFe12O19 and BaFe12O19 ferrites have a high magnetocrystalline anisotropy due to the ions at the 2 b site. The axial component at the 2 b site is weakened by the Ru doping, as it is reflected in the xrd refinements and the FT-IR spectra. Accompanied with this, the coercivity of SrFe12-xRuxO19 decreases from 4.38 kOe in x = 0 to 0.68 kOe in x = 0.5 and 0.42 kOe in x = 1.5. That of BaFe12-xRuxO19 decreases from 2.47 kOe in x = 0 to 1.10 kOe in x = 1.0. With high magnetocrystalline anisotropies, the ferromagnetic resonance (FMR), above 40 GHz, of both BaFe12O19 and SrFe12O19 falls out of 0.1–18 GHz. In BaFe12-xRuxO19 with x ≥ 0.3, FMR is observed at 14.5 GHz in 0.1–18 GHz, but the reflection loss (RL) is very low with RL ≥ −10 dB. In SrFe12-xRuxO19, strong microwave absorptions with RL ≤ −10 dB in 0.1–18 GHz range are observed with 0.5 ≤ x ≤ 1.5. The optimum RL is −32 dB observed in x = 1.0 and 1.3, and the widest bandwidth is 6.55 GHz in x = 1.0 with the thickness as 2.3 mm. In x = 0.5, RL ≤ −10 dB occurs in 14.2–18 GHz. As the Ru content varies, the microwave absorption of SrFe12-xRuxO19 fully covers a large frequency range of 4.0–18 GHz. The Ru doping drives SrFe12-xRuxO19 (0.5 ≤ x ≤ 1.5) become good microwave absorbing materials in 0.1–18 GHz.

Preparation of Magneto Electric (Bafe12o19 / Bifeo3) Composites using Sol-Gel Auto Combustion Method

The coexistence of ferromagnetic and ferroelectric properties in single phase material leads to the existence of new type of material known as magnetoelectric. In present work, magneto electric composites BaFe12O19 / BiFeO3 with different mass percentage of BiFeO3 (0, 25%, 50%, 75% and 100 %) were prepared. BaFe12O19 (BHF) and BiFeO3 (BiF) ferrites were prepared separately using Sol-gel auto combustion method and then physically mixed. Prepared composite samples were characterized using FTIR, XRD, SEM and VSM. XRD spectra reveal the mixed hexaferrite and bismuth ferrite phases. SEM micrograph of showed the formation of porous clusters of non uniform grains in the composites. Saturation magnetization of BaFe12O19 / BiFeO3 composites decreased gradually with increasing in BiFeO3 content and there is no systematic change in coercivity values.

The Enhancement of Thermomagnetic Properties for BaFe12O19 by Trivalent Ion Substitutions

The effect of trivalent ions (Al3+, Bi3+, and Mn3+) substitutions on magnetocaloric effect (MCE) of M-type ferrite BaFe12O19 (BaM) has been investigated by a phenomenological model. It is shown that the presence of Al3+, Bi3+, and Mn3+ ions in BaM makes remarkable variations for MCE. It is concluded that MnBaFe11O19 is more practical than BaM, BiBaFe11O19, and AlBaFe11O19 due to a larger MCE, and its Curie temperature is closer to room temperature. MCE of BaM can be tuning with remarkable values by doping suitable ions.

Effect of sintering temperature variations of barium hexa ferrite on physical properties and crystal structure

A Barium hexa ferrite BaFe12O19 permanent magnet has been made by using raw materials barium carbonate BaCO3 and hematite Fe2O3. The raw materials such as BaCO3 and Fe2O3 were mixed according to the composition mole ratio BaO:Fe2O3 = 1:6, then calcined at 1050°C for one hour. The calcined powder was then crushed by using hand mortar and then mixed with WE-518 celuna as muchas 3 % wt. The powder was compacted with 8 tons force to form a pellet. Further the pellets were sintered at a temperature of 1150°C, 1200°C and 1250°C with holding time one hour. The sintered samples were characterized such as: physical properties measurement (density and porosity) and micro structure analysis using XRD and magnetic properties testing measurement by vibration sample magnetometer. The characterization results show that the sample with sintering temperature of 1250°C had the highest density value of 1.43 g/cm3 and the lowest porosity value was 4.16 %. From the XRD results show that the sample that was sintered 1150°C had a single phase BaFe12O19, while the samples that had been sintered 1200°C and 1250°C were obtained in two phases, namely dominant phase is BaFe12O19 and minor phase is Fe2O3. Of the three samples tested by VSM, samples with a sintering temperature of 1150°C have good conditions and magnetic properties greater than both. the sintering temperature affects the value of each category of magnetic properties of the sample.

Magnetic properties of sintered CoFe2O4–BaTiO3 particulate magnetoelectric composites

Abstract The magnetic properties of sintered particulate magnetoelectric CoFe2O4−BaTiO3 composites have been studied. The particulate composites are sintered in the temperature range 1000–1300 °C, for a short duration of 10 min. The magnetic transition temperature (Tc) of CoFe2O4 is found to decrease with increasing the sintering temperature and sintering time, as well as on increasing the BaTiO3 content in the composites. Similarly, a reduced saturation magnetization at room temperature, compared to that expected for the CoFe2O4 content, is also observed. Powder X-ray diffraction studies showed the presence of the impurity phase related to the hexagonal ferrite BaFe12O19 in all the composites. Ba2Fe2Ti4O13 is observed as a second impurity phase in the BaTiO3−rich composites. The present studies suggest that the composition of the piezomagnetic (CoFe2O4) phase in the CoFe2O4−BaTiO3 magnetoelectric composite is affected during the sintering process.

An Attempt to Utilize Hard Magnetic BaFe12O19 Phase as a Cathode for Magnesium Batteries

The sluggish Mg2+ kinetics in host materials is a big challenge that hinders realizing practical magnesium batteries. To overcome this problem, designing and testing a new system as a fast Mg2+ insertion cathode is a promising solution. Herein, hexagonal barium ferrite BaFe12O19 as cathode for magnesium ion batteries is presented for the first time. The M ferrite phase BaFe12O19 is synthesized via the co-precipitation method. X-ray diffraction confirms single hexagonal ferrite phase with lattice constants a = b = 5.49 A and c = 23.8 A. Transmission electron microscopy images reflect high porosity with rough surfaces for the ferrite particles. The magnetic study shows that present hexaferrite has a high value of coercivity (5.1 KOe) and saturation magnetization (54 emu/gm). The electrical conductivities are studied as a function of temperature and frequencies. The multi-conduction mechanisms and multilyers structures present in these types of ferrite, make it acceptable for Mg2+ intercalation. The as-prepared BaFe12O19 electrode delivers high initial discharge capacity of 170 mAh g−1. The BaFe12O19 is a promising cathode material for magnesium-ion battery applications.

Selective EHF absorber based on BaFe12O19 hexaferrite

The results of the study of the electromagnetic response of the hexagonal ferrite composite BaFe12O19 in the frequency range 34–250 GHz at room temperature are presented. At a frequency of 46.5 GHz a region of natural ferromagnetic resonance was found. The possibility of creating a selective EHF absorber based on the developed material is shown.

Effect of Magnetic Pulse Processing on the Structure and Magnetic Properties of Ferrites

The effect a pulsed magnetic field has on the crystal structure and macroscopic magnetic parameters of hexagonal ferrites BaFe12O19 and SrFe12O19 are studied. It is shown that changes in the physical properties of ferrites are due to the ordering of cation vacancies on the boundaries of hexagonal and spinel blocks that minimize local distortion of the oxygen polyhedrons. Violation of the collinear ordering of the magnetic moments of iron ions in the nonequivalent positions of SrFe12O19 ferrite is observed, due to the selective localization of such vacancies (and thus violations of the magnetic relationships in Fe–O–Fe).

Study of the sintering temperature and the sintering time period effects on the structural and magnetic properties of M-type hexaferrite BaFe12O19

The hexagonal ferrite BaFe12O19 (BaM) has been prepared by the citrate precursor method. The synthesized sample has been sintered at 1000, 1100 and 1200 °C for 24 h and 1300 °C for 62, 124 and 148 h to examine the effect of both sintering temperature and sintering duration on the structure and the magnetism of BaM. So these samples have been characterized by XRD, FT-IR, VSM, SEM and TEM techniques. The XRD and SEM images show that increasing sintering temperature has enhanced the purity and crystallinity of the samples with grain growth from 0.537 μm to 16.35 μm. In addition, the single crystal has been formed into the sample 1300 °C/62 h. On the other hand, the crystallinity deterioration has occurred with increasing sintering period and a barium oxide phase (BaO) has appeared. The IR spectra show three fundamental absorption bands ν1, ν2 and ν3 of hexagonal ferrite corresponding to tetrahedral and octahedral complexes. The intensity of the absorption bands increases by improving the crystallinity which resulting from the sintering process. From the VSM measurements, the maximum recorded magnetization values (Mm), the remnant magnetization (Mr), the squareness ratio Mr/Mm and the coercivity (Hc) of the samples have been recorded. As a result of grain growth, the transformation of the single domain to the multi-domain structure occurs. This can be supported by noticing the reduction of Hc values with grain growth.

Features of crystal structure and texture of isotropic and anisotropic polycrystalline hexagonal ferrites BaFe12O19, obtained by the method of radiation-thermal sintering

Features of crystal structure and texture of isotropic and anisotropic polycrystalline hexagonal ferrites BaFe12O19, obtained by the method of radiation-thermal sintering