Barium Hexaferrite Nanoparticles Research Articles

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.

Influence of tetraethyl orthosilicate coating on dielectric, impedance, and modulus properties of barium hexaferrite nanoparticles prepared by a modified sol–gel method

This work is devoted to study the comparison of the conduction mechanism in bare barium hexaferrite (BaFe12O19) nanoparticles and tetraethyl orthosilicate-coated (SiO2)x/BaFe12O19 (x = 5, 10, 15 and 20 wt. %) nanoparticles. The modified sol–gel method was adopted for the synthesis of these nanoparticles. The structures, morphologies, elemental composition, vibrational modes, and dielectric properties of these nanoparticles were studied by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and dielectric measurements, respectively. The crystallite size and particle size of BaFe12O19 nanoparticles decreased with SiO2 coatings, which can be attributed to the confinement of crystal growth of these nanoparticles with the coating. It was found that these (SiO2)x/BaFe12O19 nanoparticles have a uniform spherical shape, are non-agglomerated, and have a narrow particle size distribution. At room temperature, these (SiO2)x/BaFe12O19 nanoparticles showed distinctive behavior with varying frequency and SiO2 coatings. The experimental results in this work may provide fundamental support to the research and development of materials for energy storage devices.

Effect of ferromagnetic cobalt on characteristics of coercive Aluminium substituted BaFe11.5Al0.5O19 hexaferrites

Magnetic and structural characteristics of M-type barium hexaferrite nanoparticles can be tuned by doping different di or trivalent metal ions. Here BaFe11.5−xAl0.5CoxO19 hexaferrite nanoparticles were synthesized using a sol-gel process, and the influence of doping concentrations on M-type BaFe11.5−xAl0.5CoxO19 hexaferrite nanoparticles was deliberated. The XRD analysis confirms the formation of ferrites successfully. When the doping level increased, the grain dimension (D) initially reduced and then increased. Similarly, the lattice constants ‘a’ and ‘c’ decreased initially and then increased. The findings indicated that the (Mr/Ms) ratio decreased initially as the doping content increased, but at higher doping ranges, it started to rise. At the same time, coercivity (Hc) and magneto-crystalline an-isotropy field (Ha) increased as the doping level increased. Excellent magnetic characteristics were obtained for BaFe11.5−xAl0.5CoxO19 hexaferrites at doping content of (x = 1.5), with magnetic moment 10.80 μ B, saturation magnetization 57.35 emu g−1, and coercivity 5.21 kOe along anisotropic applied field of 1.62 kOe. The findings mentioned above imply that magnetic characteristics of M-type Barium hexaferrites can be significantly improved upon doping of Cobalt against Aluminium substituted hexaferrites, which will make such types of Ba-hexaferrites very useful in various magnetic applications.

Broadband Electromagnetic Properties of Engineered Flexible Absorber Materials

AbstractFlexible and stretchable materials have attracted significant interest in wearable electronics and bioengineering fields. Recent developments also incorporate embedded microwave circuits and systems with engineered flexible materials that operate over a broad frequency range (≈1–100 GHz). Herein, a simple flip‐chip technique is used to evaluate frequency‐dependent electromagnetic properties of flexible materials and applied to evaluate engineered microwave absorbers based on self‐biased barium hexaferrite composites. On‐wafer error correction and de‐embedding techniques are applied to determine broadband electromagnetic properties of the material‐loaded transmission lines by placing the materials on top of coplanar waveguide transmission lines. Finite‐element simulations along with broadband measurements were employed to estimate the electromagnetic material properties. To demonstrate, flexible polydimethylsiloxane (PDMS) composites are fabricated with barium hexaferrite nanoparticles and complex permittivity and permeability of the composites are quantified under zero magnetic field bias up to 110 GHz. Frequency‐dependent composite permeability is fitted to models describing the ferromagnetic resonance of the self‐biased barium hexaferrite nanoparticles in polydimethylsiloxane, and constituent nanoparticle properties are estimated using the Maxwell–Garnett mixing model. This study paves the way to exploit a wide range of engineered materials in flexible, wearable, and biomedical electronics applications and presents a convenient methodology to extract important broadband electromagnetic properties of nanoparticles for customized electromagnetic applications.

Zn and Ni doping effect on barium hexaferrite ferroelectric, optical properties and photocatalytic activity under visible light irradiation

In this study, we explored the potential photocatalytic activity of doped ferrites by examining the effects of zinc and nickel doping on barium hexaferrite (Ba1-xZnxFe12-yNiyO19) nanoparticles. To prepare the samples, we utilized a micro-emulsion approach and evaluated the influence of dopants on their structural, ferroelectric, and photocatalytic properties. The X-ray diffraction and Raman spectra indicated that the synthesized samples were hexagonal and belonged to the P63/mmc space group. The average crystallite size has been calculated in the range of 64–67 nm. By enhancing the dopant concentration, the optical bandgap decreased from 2.19 (eV) to 1.48 (eV). The material with a narrow bandgap is useful for catalytic application and PL signal was also revealed low-rate recombination of e−-h+ pair. Moreover, photo-degradation experiment was carried out by degrading the methyl violet dye under visible light irradiation. The highly substituted material furnished 87% of dye removal, which was 56% in case of undoped sample. The Ba1-xZnxFe12-yNiyO19 material demonstrates great potential as a photocatalyst for the degradation of dyes in effluents when exposed to visible light. This finding suggests that this material could be a valuable solution for addressing the challenges posed by dye contamination in wastewater.

Enhancement of Microwave Absorption Properties of Hexaferrite/Epoxy Composites on the Addition of Non-magnetic Oxides

The effect of non-magnetic oxides such as Al2O3, TiO2 and ZnO on the microwave absorption properties of magnetoplumbite barium hexaferrite (BaFe11.8Co0.2O19) is analyzed. Barium hexaferrite nanoparticles are synthesized through the sol-gel auto-combustion method. BaFe11.8Co0.2O19-Al2O3, BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO composites are synthesized in a 1:1 ratio through mechanical mixing and heat treatment. The epoxy composites are fabricated with 50% loading of BaFe11.8Co0.2O19-Al2O3, BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO in epoxy matrix followed by room temperature curing. The powder XRD analyses showed homogeneous distribution of BaFe11.8Co0.2O19 and Al2O3 in BaFe11.8Co0.2O19-Al2O3 composite while TiO2 and ZnO phases dominate in BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO composites, respectively. Scanning electron microscopy shows the evenly distributed BaFe11.8Co0.2O19 and Al2O3 in BaFe11.8Co0.2O19-Al2O3 composites. The electromagnetic characterization calculated from experimental permittivity and permeability shows reflection loss RL ≤ -10 dB (≥ 90% absorption) for a very small thickness of 0.5 mm over the entire X-band (8-12 GHz) for BaFe11.8Co0.2O19-Al2O3 composites. BaFe11.8Co0.2O19-TiO2 and BaFe11.8Co0.2O19-ZnO show RL < - 8 dB with a thickness of 2.5 mm over the frequency range 8–9.7 GHz and RL < - 8 dB with a thickness of 3.6 mm over 8.7-11.1 GHz, respectively. Further, when compared with BaFe11.8Co0.2O19 alone (RL < -7 dB at 3.2 mm in 8-11 GHz), the BaFe11.8Co0.2O19-Al2O3 composite is superior both in terms of the thickness of the coating as well as the percentage absorption in the X-band.

Magnetic and microwave absorption properties of Co2+ and Zn2+ co-doped barium hexaferrite nanoparticles

Magnetic and microwave absorption properties of Co2+ and Zn2+ co-doped barium hexaferrite nanoparticles

The effect of agarose agent on the structural, magnetic and optical properties of barium hexaferrite nano-particles synthesized by sol-gel auto-combustion method

The main goal of this study is to improve the structural, magnetic and optical properties of the M-type barium hexaferrite nano-particles by addition of agarose as a natural agent, which were synthesized by the sol-gel auto-combustion method. For this purpose, properties of the synthesized samples were characterized by DTA-TGA, XRD, FT-IR, FE-SEM, TEM, VSM, and UV–Vis-DRS analyses. The DTA-TGA thermal analyses showed that agarose as a fuel agent could reduce the starting temperature of crystallization in the precursors. Also, based on these results, the temperature of 800 °C was chosen as the calcination temperature of the precursors. XRD patterns confirmed the formation of pure M-type barium hexaferrite without any impurities after calcination at 800 °C. The presence of agarose caused a more homogeneous distribution of metal cations Fe3+ and Ba2+ and the precursor was more easily and completely transformed into hexagonal barium ferrite in the presence of this agent. Also, the Rietveld refinement reported a decrease in average crystallite size from 49.4 to 29.6 nm by adding agarose. In addition, FE-SEM and TEM images showed that the agarose agent significantly reduces the average particle size and also prevents agglomeration of particles. Moreover, magnetic studies indicated that the presence of agarose led to the simultaneous increase of coercivity and remanence magnetization, resulting in an increase of maximum energy product from 0.81 to 0.92 MGOe. Also, the band gap energy (Eg) of the synthesized samples was found in the range of 2.36–2.76 eV. Finally, the significant effect of the agarose agent on the properties of BaFe12O19 nano-particles was clearly explained.

Sol-gel auto-combustion synthesis of double metal-doped barium hexaferrite nanoparticles for permanent magnet applications

In the current work, BaZnxZrxFe12-2xO19 (x ​= ​0.00–0.15) sub-micron particles synthesis with the help of the sol-gel auto-combustion technique has been carried out. XRD studies reveal the single BaM (barium hexaferrite of M-type) phase formation and undesirable phases such as BaFe2O4 and α–Fe2O3 absent. The FE-SEM micrographs suggest that the size of grain increases from ≈241 ​nm (x ​= ​0.00) to ​≈ ​280 ​nm (x ​= ​0.15) with a substitution level. The enhancement in grain size with composition has been also confirmed by the dynamic light scattering technique (DLS). The coercivity (Hc) has been continuously decrease from 5363 ​Oe (x ​= ​0.00) to 4211 ​Oe (x ​= ​0.15) with increase in non-magnetic dopant concentration. On the other hand, the saturation magnetization (Ms) value increases from 70.87 emu/g (x ​= ​0.00) to 87.04 emu/g (x ​= ​0.15) with substitution. In the sol-gel auto-combustion synthesis of M-type hexaferrite, fuel plays an important role. It affects the magnetic properties, surface morphology, and calcination temperature of hexaferrite. In the present study, synthesis of Zr4+-Zn2+ doped BaM having a low composition (x ​= ​0.00–0.15) using tartaric acid as fuel is first reported. The enhanced magnetic properties of Zr4+-Zn2+ doped BaM samples over undoped samples can be used in permanent magnet appliances.

Synergistic influence of barium hexaferrite nanoparticles for enhancing the EMI shielding performance of GNP/epoxy nanocomposites

Synergistic influence of barium hexaferrite nanoparticles for enhancing the EMI shielding performance of GNP/epoxy nanocomposites

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.

Zn and Mn doped Ba1-xZnxFe12-yMnyO19 as highly photoactive under visible light with enhanced electrochemical and dielectric properties

The zinc and manganese substituted barium hexaferrite (Ba1-xZnxFe12-yMnyO19) nanoparticles (0.00 < x < 0.90; 0.00 < y < 0.75) was fabricated by microemulsion approach and effect of substitution was evaluated on the basis of electrochemical, dielectric and photocatalytic properties. The Ba1-xZnxFe12-yMnyO19 NPs exhibited ferrite structure with hexagonal phase having P63/mmc space group and the crystallite size was in 16–21 nm range. The microstructure of Ba1-xZnxFe12-yMnyO19 NPs showed the agglomerated spherical structure. The effect of doping on the electrochemical property of the fabricated material was investigated via cyclic voltammetry. The energy band gap was estimated from UV–visible absorbance spectra using Tauc plots, band gap values show a decreasing trend by increasing the dopant contents, i.e., 1.89 (eV) to 1.31 (eV) for doped samples. The low band gap value material has promising potential in optical and catalytic applications. Dielectric constant and dielectric loss of Ba1-xZnxFe12-yMnyO19 NPs were monitored in 20 Hz to 0.017 GHz range. By increasing the dopants content, tangent loss and dielectric loss were increased, while the AC conductivity was decreased. Moreover, photocatalytic efficiency was investigated by degrading methyl green (MG) dye under visible light irradiation and it was found that the substituted NPs exhibited maximum degradation of 85.1% of MG dye following the first order kinetic with rate constant of 0.0188 min−1. The results depict that the properties of BaFe12O19 can be tuned by Zn and Mn doping for potential application in photocatalysis.

Water-annealing regulated protein-based magnetic nanofiber materials: tuning silk structure and properties to enhance cell response under magnetic fields

In this study, flexible silk fibroin protein and biocompatible barium hexaferrite (BaM) nanoparticles were combined and electrospun into nanofibers, and their physical properties could be tuned through the mixing ratios and a water annealing process. Structural analysis indicates that the protein structure of the materials is fully controllable by the annealing process. The mechanical properties of the electrospun composites can be significantly improved by annealing, while the magnetic properties of barium hexaferrite are maintained in the composite. Notably, in the absence of a magnetic field, cell growth increased slightly with increasing BaM content. Application of an external magnetic field during in vitro cell biocompatibility study of the materials demonstrated significantly larger cell growth. We propose a mechanism to explain the effects of water annealing and magnetic field on cell growth. This study indicates that these composite electrospun fibers may be widely used in the biomedical field for controllable cell response through applying different external magnetic fields.

Structural, microstructural, magnetic and electromagnetic absorption properties of spiraled multiwalled carbon nanotubes/barium hexaferrite (MWCNTs/BaFe12O19) hybrid

Microwave absorption properties were systematically studied for synthesised barium hexaferrite (BaFe12O19) nanoparticles and spiraled multiwalled carbon nanotubes (MWCNTs) hybrid. BaFe12O19 nanoparticles were synthesised by a high energy ball milling (HEBM) followed by sintering at 1400 °C and structural, electromagnetic and microwave characteristics have been scrutinized thoroughly. The sintered powders were then used as a catalyst to synthesise spiraled MWCNTs/BaFe12O19 hybrid via the chemical vapour deposition (CVD) process. The materials were then incorporated into epoxy resin to fabricate single-layer composite structures with a thickness of 2 mm. The composite of BaFe12O19 nanoparticles showed a minimum reflection loss is − 3.58 dB and no has an absorption bandwidth while the spiraled MWCNTs/BaFe12O19 hybrid showed the highest microwave absorption of more than 99.9%, with a minimum reflection loss of − 43.99 dB and an absorption bandwidth of 2.56 GHz. This indicates that spiraled MWCNTs/BaFe12O19 hybrid is a potential microwave absorber for microwave applications in X and Ku bands.

Evaluation of structural, dielectric, magnetic and photocatalytic properties of Nd and Cu co-doped barium hexaferrite

In this study, the micro-emulsion approach was adopted to fabricate rare earth (Nd) and transition metal (Cu) co-doped barium hexaferrite (Ba1-xNdxFe12-yCuyO19) nanoparticles (NPs). The fabricated co-doped and undoped materials were characterized by FTIR, XRD, and SEM techniques for structural and morphological investigation. Structural studies such as XRD and FTIR confirmed Nd and Cu doping at the tetrahedral and octahedral sites of barium hexaferrite, respectively. The SEM analysis made sure that the materials were successfully produced at the nanoscale. Dielectric measurements revealed that the dielectric constant and AC conductivity values of the co-doped sample were higher than those of the undoped sample. The VSM study confirms the improved magnetic properties of the sample after co-doping that facilitates its separation and reuse after photocatalytic experiments. The co-doped and undoped sample's photocatalytic activities (PCA) were explored by comparing their Methyl Green (MG) dye degradation efficiencies. The results revealed that the co-doped barium hexaferrite sample degraded almost 92.6% of the MG dye, while the undoped sample degraded just 37.4%. The higher PCA of the co-doped sample is credited to its structural defects, which adjust the band interval to increase electrical conductivity. In addition, the co-doped sample lost only 2% photocatalytic efficiency after five successive cycles, demonstrating its potential for reuse. Application studies have clearly shown that our Nd-Cu co-doped barium hexaferrite sample has a great potential for practical application to remove toxic dyes from the environment.

Carboxylation-induced polyaniline morphology on surfaces of barium hexaferrite nano particles with enhanced microwave absorbing properties

Surface carboxylation of barium hexaferrite (BaM) has been successfully established, which effectively promotes the interaction of BaM and PANI chains and provides activated points for the preferential growth of polyaniline (PANI) on the surfaces of BaM particles. Based on this, the morphology of PANI layer has been tuned from irregular shape to convex rods and dendrite. Both convex rods and dendrite-like morphology activate electron transport in the PANI chain and enhance interfacial polarization between PANI and BaM, resulting in an improved complex permittivity. BaM particles with PANI convex rods on the surfaces exhibit an excellent and broad microwave absorption due to enhanced electromagnetic wave dissipation in the local micro-domains and the combination of dielectric loss, magnetic loss as well as interfacial loss.

Ce–Dy substituted barium hexaferrite nanoparticles with large coercivity for permanent magnet and microwave absorber application

M-type barium hexaferrites (BaM) with the substitution of Ce–Dy ions were synthesized using the sol-gel auto-ignition method. The prepared materials were explored for their application as a permanent magnet and microwave absorbing material. The structural properties, phase evaluation, micro-strain, morphological analysis, magnetic behaviour, microwave absorbing properties and optical properties were studied by employing various techniques. The structural parameters and phase identification obtained by Rietveld refinement confirmed the formation of an M-type hexaferrite structure for pure BaM, whereas Ce–Dy substitution induced secondary phases of cubic CeO2 and ortho DyFeO3. Crystallite size obtained from Williamson–Hall plots increased from 27.1 nm to 30.8 nm with the introduction of Ce–Dy ions in BaM. The nanocrystalline nature of the prepared samples was confirmed using scanning and transmission electron microscopy techniques. Fourier transform infrared spectra of all the samples were recorded in the wavenumber range of 400–4000 cm−1 and also supported the x-ray diffraction findings by confirming the formation of samples with hexaferrite structures. Coercivity of the BaM hexaferrites improved from 4430 to 5721 Oe with the Ce–Dy substitution. A Ce–Dy substituted BaM hexaferrite sample of 3 mm thickness showed a maximum reflection loss of −16.3 dB around 16.7 GHz. Permittivity and permeability studies were carried out to understand the microwave absorption behaviour.

PVC based flexible nanocomposites with the incorporation of Polyaniline and Barium Hexa-Ferrite nanoparticles for the shielding against EMI, NIR, and thermal imaging cameras

The chemical oxidative method was used for the polymerization of the polyaniline (PANI) by the use of ammonium persulphate as oxidant and formic acid as a dopant. The co-precipitation method was for the precipitation of barium Hexaferrite (BaFe). By the use of polyaniline, polyvinyl chloride, and barium Hexaferrite the magnetic and electrically conductive polymer nanocomposites films were synthesized with a solution casting method having a thickness of 0.5 mm. Enhanced EMI shielding effectiveness was achieved with very less nanocomposite film thickness using novel combination of electrically conductive polymer and ferrite nanoparticles. The effects of synthesis parameters on the features of the subsequent nanocomposites like near-infrared (NIR) transmission, electrical conductivity, tensile strength, and electromagnetic interference (EMI) shielding effectiveness by absorbance and reflection was examined in the frequency region of 0.1–20 GHz. The electrically conductive nanocomposites were characterized by XRD, UV/Vis/NIR spectroscopy, SEM, VNA, 2-Probe Method, and thermal images. The different concentrations of polyaniline and barium Hexaferrite result in different electrical conductivity values, mechanical properties, transmission value, and shielding efficiencies at the 0.1–20 GHz frequency range. The maximum attenuation achieved by PVC/PANI nanocomposites was 43.76 dB while PVC/PANI/BaFe nanocomposites have 78 dB.

Microwave absorption study of low-density composites of barium hexaferrite and carbon black in X-band

The low-density composites based on carbon black (CB) nanopowder and barium hexaferrite (BaFe12O19) nanoparticles are synthesized and characterized for microwave absorption properties in X-band (8.2–12.4 GHz). Barium hexaferrite nanoparticles are developed using low-cost autocombustion method that resulted in low-density particles with uniform particle size distribution. Composites are developed by the ball-milling of BaFe12O19 with CB nanopowder in different weight ratios followed by heat-treatment process. The addition of CB in the composite resulted in enhanced electrical properties due to increase in the dipolar polarization between carbon and ferrite. As a result of increasing CB concentration in composite, the dielectric loss tangent increased from 0.31 to 0.366. On the contrary, the magnetic loss tangent decreased from 0.071 to 0.027, which is due to reduction of magneto-crystalline anisotropy of the composite with CB addition. The composite medium containing 80% CB and 20% BaFe12O19 showed excellent microwave absorption properties having minimum reflection loss of −56.266 dB at 11.98 GHz for an effective coating thickness of 1.85 mm. Also, the effective bandwidth of the composite having reflection loss of 90% (−10 dB) reached to 3.53 GHz (84% of X-band) for coating thickness 2.15 mm. The low reflection loss and wide bandwidth microwave absorption of the composite is due to the increased dielectric properties, which resulted in better impedance matching with free space and high electromagnetic (EM) attenuation.

Synthesis, characterization and optical properties of rare earth doped barium hexaferrite nano particles

In this work we have prepared a series of BaFe12O19 :xEu3+ (x=0 to 2 mol %) samples by combustion method. The prepared samples were characterized by PXRD, TEM and FTIR. The structural analysis of PXRD pattern affirms that the specimens have space group p63/mmc and hexagonal structure. The TEM micrographs show hexagonal plate like structure and the FTIR spectra show vibration between the 4f1 and 4f2 crystallographic sites of the ferric ions. The absorption spectra of the prepared specimen were obtained from UV-vis spectroscopy. The calculated band gap values range from 3.99 eV to 2.29eV.