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With the proliferation of electronics and wireless devices, managing disruptive electromagnetic interference (EMI) has become imperative. This review examines recent advancements in magnetic nanocomposite materials for EMI shielding applications. Fundamentally, these multifunctional nanocomposites leverage the synergy between magnetic and conductive components to facilitate exceptional microwave absorption and reflection capabilities. The analysis begins by elucidating the physics of EMI shielding mechanisms, including reflection, absorption, and multiple internal reflections. Building on electromagnetic principles, the magnetic properties of nanocomposite constituents are discussed, emphasizing their role in enabling magnetic loss, dielectric loss, and eddy current induction within materials. The review then extensively explores common synthesis techniques for magnetic nanocomposites, such as co-precipitation, sol–gel, and hydrothermal methods. A detailed examination of the resulting nanocomposite characteristics and EMI shielding performance provides useful insights into composition-structure–property relationships. Moreover, innovative fabrication strategies based on physical vapor deposition are highlighted for their precision in controlling nanostructure morphology. Subsequently, the review dives into the nuanced interplay between dielectric, conductive, and magnetic nanocomposite components and their synergistic influence on EMI shielding. Current challenges are also discussed, encompassing issues like nanoparticle agglomeration and environmental durability. Finally, scalable production methods are reviewed as a crucial step towards real-world applications. This all-encompassing review synthesizes the frontiers of magnetic nanocomposite engineering, design, and fabrication for next-generation EMI shielding materials with tailored, application-specific shielding capabilities.

Microwave absorption properties were systematically studied for synthesised barium hexaferrite (BaFe 12 O 19 ) nanoparticles and spiraled multiwalled carbon nanotubes (MWCNTs) hybrid. BaFe 12 O 19 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/BaFe 12 O 19 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 BaFe 12 O 19 nanoparticles showed a minimum reflection loss is − 3.58 dB and no has an absorption bandwidth while the spiraled MWCNTs/BaFe 12 O 19 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/BaFe 12 O 19 hybrid is a potential microwave absorber for microwave applications in X and Ku bands.

The enhancement of microwave absorbing properties in nickel zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4 ) via multiwall carbon nanotubes (MWCNT) growth is studied in this research work. Ni 0.5 Zn 0.5 Fe 2 O 4 was initially synthesized by mechanical alloying followed by sintering at 1200 °C and the microstructural, electromagnetic and microwave characteristics have been scrutinized thoroughly. The sintered powder was then used as a catalyst to grow MWCNT derived from chemical vapor deposition (CVD) method. The sample was mixed with epoxy resin and a hardener for preparation of composites. The composite of multi-walled carbon nanotubes/Ni 0.5 Zn 0.5 Fe 2 O 4 shown a maximum reflection loss ( RL ) of −19.34 dB at the frequency and bandwidth of 8.46 GHz and 1.24 GHz for an absorber thickness of 3 mm for losses less than −10 dB. This acquired result indicates that multi-walled carbon nanotubes/Ni 0.5 Zn 0.5 Fe 2 O 4 could be used as a microwave absorber application in X-band.

In this study, magnetite nano-adsorbent (MNA) was extracted from mill scale waste products, synthesized and applied to eliminate Cu2+ from an aqueous solution. Mill scale waste product was ground using conventional milling and impacted using high-energy ball milling (HEBM) for varying 3, 5, and 7 milling hours. In this regard, the prepared MNA was investigated using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), field emission scanning electron microscopy–energy-dispersive X-ray spectroscopy (FESEM-EDS), UV–Vis spectroscopy, Fourier-transform infrared (FTIR), Brunauer–Emmett–Teller (BET) and zeta potential. The resultant MNA-7 h milling time displayed a crystalline structure with irregular shapes of 11.23 nm, specific surface area of 5.98 m2g−1, saturation magnetization, Ms of 8.35 emug−1, and isoelectric point charge at pH 5.4. The optimum adsorption capacity, qe of 4.42 mg.g−1 for the removal of Cu2+ ions was attained at 120 min of contact time. The experimental data were best fitted to the Temkin isotherm model. A comparison between experimental kinetic studies and the theoretical aspects showed that the pseudo-second-order matched the experimental trends with a correlation coefficient of (R2 > 0.99). Besides, regeneration efficiency of 70.87% was achieved after three cycles of reusability studies. The MNA offers a practical, efficient, low-cost approach to reutilize mill scale waste products and provide ultra-fast separation to remove Cu2+ from water.

Calcium oxide from discarded eggshells and waste soda-lime-silica were utilized in this study to make wollastonite (CaSiO3) based glass-ceramics. The calcium oxide and silica were made using the melt-quenching process and sintered for 2 hours at 700 to 1000 ?C. The XRD data verified that the wollastonite crystalline peak appeared at high sintering temperatures, with crystalline phase values of 39.74%, 47.37%, and 48.91% as the sintering temperature increased at 800-1000?C, respectively. Additionally, crystalline size and phase have no obvious change at 800-1000?C, where the intensity has increased by the sintering temperature. The FTIR spectra revealed the wollastonite phase vibration at the wavelength of 501, 650, 715, 808, 931, and 2129 cm-1. Additionally, the FTIR spectral confirm the Si-O-Ca vibration band at the wavelength of 650 cm-1. For the optical sample, the value of indirect allowed transition with n=2 is the ideal value of the optical band gap based on a band gap rise from 3.89 to 4.23 eV with increasing sintering temperature. The value n=2 which is the indirect allowed transition is the optimal value of the optical band gap based on the value increase from 3.89-4.23 eV as the temperature increase. The synthesis approach introduced the low-cost method, recycle approach, simple and yet uses cheap starting materials for fabrication of wollastonite glass-ceramics product.

This study presents the utilization of mill scale waste, which has attracted much attention due to its high content of magnetite (Fe3O4). This work focuses on the extraction of Fe3O4 from mill scale waste via magnetic separation, and ball milling was used to fabricate a microwave absorber. The extracted magnetic powder was ground-milled using two different techniques: (i) a conventional milling technique (CM) and (ii) mechanical alloying (MM) process. The Fe3O4/CM samples were prepared by a conventional milling process using steel pot ball milling, while the Fe3O4/MM samples were prepared using a high-energy ball milling (HEBM) method. The effect of milling time on the structural, phase composition, and electromagnetic properties were examined using X-ray diffraction (XRD) and a vector network analyzer (VNA). XRD confirmed the formation of magnetite after both the magnetic separation and milling processes. The results revealed that Fe3O4 exhibited excellent microwave absorption properties because of the synergistic characteristics of its dielectric and magnetic loss. The results showed that the Fe3O4/CM particle powder had a greater absorption power (reflection loss: <−10 dB) with 99.9% absorption, a minimum reflection loss of −30.83 dB, and an effective bandwidth of 2.30 GHz for 2 mm thick samples. The results revealed the Fe3O4/MM powders had higher absorption properties, including a higher RL of −20.59 dB and a broader bandwidth of 2.43 GHz at a matching thickness of only 1 mm. The higher microwave absorption performance was attributed to the better impedance matching property caused by the porous microstructure. Furthermore, the magnetite, Fe3O4 showed superior microwave absorption characteristics because of the lower value of permittivity, which resulted in better impedance matching. This study presents a low-cost approach method by reutilizing mill scale waste to fabricate a high purity crystalline Fe3O4 with the best potential for designing magnetic nano-sized based microwave absorbers.

The present study synthesized nano-magnetite (Fe3O4) from milled steel chips using the high energy ball milling (HEBM) method, characterized it, and then utilized it as a sorbent to remediate boron concentration at various pH (4–9), dosages (0.1–0.5 g), contact times (20–240 min), and initial concentrations (10–100 mg/L). The nano-sorbents were characterized based on SEM structure, elemental composition (EDX), surface area analysis (BET), crystallinity (XRD), and functional group analysis (FTIR). The highest adsorption capacity of 8.44 mg/g with removal efficiency of 84% was attained at pH 8, 0.5 g dosage, contact time of 180 min, and 50 mg/L initial concentration. The experimental data fit best with the pseudo-second-order kinetic model with R2 of 0.998, while the Freundlich adsorption isotherm describes the adsorption process with an R2 value of 0.9464. A regeneration efficiency of 47% was attained even after five cycles of reusability studies. This efficiency implies that the nano-magnetite has the potential for sustainable industrial application.

Pure zinc ferrite, ZnFe 2 O 4 and aluminum-doped zinc ferrite, Al: ZnFe 2 O 4 (0.5% Al) nanofibers were prepared by the combination of electrospinning and calcination at different temperatures. X-ray diffraction reveals their cubic spinel structure, belonging to space group Fd-3 m (227). As the calcination temperature increases from 500 to 700 °C, the crystallite sizes of ZnFe 2 O 4 andAl: ZnFe 2 O 4 nanofibers respectively increase from 20 to 31 nm and from 18 to 30 nm. It is also observed that the crystallite sizes decrease with Al doping at all temperatures. The maximum magnetization of the samples, measured by vibrating sample magnetometer, was found to increase from 3.1533 to 7.9871 emu/g, 2.4102 to 8.0380 emu/g and 2.2038 to 2.9057 emu/g at 500 °C, 600 °C and 700 °C respectively, due to Al doping. The photocatalytic activity, as measured by RhB degradation, is found to improve with Al doping and by introduction of H 2 O 2 oxidant in photo-Fenton process.

In this research, we have presented a novel composite that is both low-cost and highly efficient. This composite is synthesized by combining Mg 0.8 Zn 0.1 Co 0.1 Fe 2 O 4 and Calcium Titanium Oxide (CTO) through a two-stage hydrothermal and coprecipitation process. The electromagnetic characteristics of the nanocomposites are effectively tuned by combining magnetic (MZCFe 2 O 4 ) nanoferrite with dielectric (CTO) nanoparticles. XRD images showed that all prepared nanocomposites formed spinel structures without secondary phases. The findings of the structural and magnetic concepts and experimental investigations exhibit good agreement, confirming the accuracy of the cation distribution. The experimentally measured lattice parameter for MZCFe 2 O 4 falls within the range of 8.3539–8.3874 Å, whereas the theoretical lattice parameter falls within the range of 8.3882–8.3833 Å. The mean crystal size was determined using the Debye–Scherrer technique, which was discovered to be between 53 and 75 nm, proving that all nanocomposites are nanocrystalline. The nanocomposite structure is shown in the FESEM micrographs, which show rocky-shaped particles with a range of hole sizes. All molecular elements are present, according to EDX bands. Mg 0.8 Zn 0.1 Co 0.1 Fe 2 O 4 /CTO (S3) nanocomposites exhibit a peak reflection loss (RL) value of -23.05 dB (99.50% absorption) at 11.4 GHz. This level of absorption is achieved with a material thickness of 2 mm and maintains effective absorption (RL ≤ 10 dB) across a bandwidth of 2.5 GHz, spanning from 11 to 13.5 GHz. The ternary composites created in this study demonstrate a significant enhancement in microwave absorption capabilities. This improved performance is credited to the innovative structural arrangement, featuring robust interfacial polarization, multiple reflections, impedance matching, and a beneficial synergistic interaction between Mg 0.8 Zn 0.1 Co 0.1 Fe 2 O 4 and CTO nanoparticles. This shows that S3 nanocomposite is a perfect candidate for high-efficiency microwave absorption. As a consequence, this method may be used to create a novel, highly effective microwave absorber.

The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5–25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3–PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector network analyzer (VNA) in the frequency range 8.2–12.4 GHz. The CTE of PTFE matrix decreased from 65.28×10−6/°C to 39.84×10−6/°C when the filler loading increased to 25 wt %. The real (ε′) and imaginary (ε″) parts of permittivity increased with the rFe2O3 loading and reached maximum values of 3.1 and 0.23 at 8 GHz when the filler loading was increased from 5 to 25 wt %. A maximum complex permeability of 1.1−j0.07 was also achieved by 25 wt % nanocomposite at 10 GHz.