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MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h. [ABSTRACT FROM AUTHOR]

To meet the challenge of varied working temperatures of inductance components in new energy vehicle and 5G communication, the high- T C high-permeability MnZn ferrite with excellent temperature stability was developed by the addition of SnO 2. In this series of samples, initial permeability μ i maintains large values in a wide temperature range. With increasing the SnO 2 content, the temperature of the second permeability peak T sp decreases and meanwhile Curie temperature T C maintains as high as 160 °C. For the best sample with 6000 ppm SnO 2 , μ i at 25 °C is 7244 and exhibits the excellent temperature stability with the low specific temperature coefficient of 0.35 × 10−6 °C−1 between 25 and 130 °C. The addition of SnO 2 generates Fe2+ and adjusts the magneto-crystalline anisotropy constant K 1 = 0 point, which is responsible for the wide-temperature high permeability. The effect of SnO 2 addition on magnetization process has also been clarified. [ABSTRACT FROM AUTHOR]

This article proposes a simulation model of single-phase common-mode inductors to evaluate the small-signal characteristic of common-mode inductors when the stray capacitance cancellation method is applied. From the estimated stray capacitance of common-mode inductors, the value of the cancellation capacitors is determined and implemented into the model. Thus, the proposed model can simulate the small-signal characteristic of common-mode inductors with the capacitance cancellation method at the design stage. To validate the proposed model, a comparison between measured and simulated attenuation characteristics of fabricated single-phase common-mode inductors is performed. The comparison result clarifies that the high-frequency attenuation improvement of the capacitance cancellation method is limited for manganese–zinc ferrite-based common-mode inductors due to the steep change of the complex permeability. [ABSTRACT FROM AUTHOR]

MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h.

Mixed manganese–zinc ferrite nanoparticles coated with PEG were studied for their potential usefulness in MRI thermometry as temperature-sensitive contrast agents. Particles in the form of an 8.5 nm core coated with a 3.5 nm layer of PEG were fabricated using a newly developed, one-step method. The composition of Mn0.48Zn0.46Fe2.06O4 was found to have a strong thermal dependence of magnetization in the temperature range between 5 and 50 °C. Nanoparticles suspended in an agar gel mimicking animal tissue and showing non-significant impact on cell viability in the biological test were studied with NMR and MRI over the same temperature range. For the concentration of 0.017 mg/mL of Fe, the spin–spin relaxation time T2 increased from 3.1 to 8.3 ms, while longitudinal relaxation time T1 shows a moderate decrease from 149.0 to 125.1 ms. A temperature map of the phantom exposed to the radial temperature gradient obtained by heating it with an 808 nm laser was calculated from T2 weighted spin-echo differential MR images. Analysis of temperature maps yields thermal/spatial resolution of 3.2 °C at the distance of 2.9 mm. The experimental relaxation rate R2 data of water protons were compared with those obtained from calculations using a theoretical model incorporating the motion averaging regime. [ABSTRACT FROM AUTHOR]

In this study, high-frequency MnZn ferrites are prepared for power applications at 10 MHz using solid-state reaction method. The sample doped with 3000 ppm TiO 2 yields the optimal comprehensive magnetic properties, with an initial permeability of 792, power loss of 415 kW/m3 (10 MHz, 5 mT, 25 ℃), and saturation induction of 460 mT. This indicates significant progress compared to previously reported results. The mechanisms of property optimisation, microstructure and domain structure evolution also discussed with TiO 2 doping. The precipitation of Ti at the grain boundary can promote a high-density microstructure and favour the formation of magnetic monodomain in MnZn ferrites. Our results elucidate the correlations between microstructure, domain structure, and high-frequency performance, and present a potential roadmap for the development of high-frequency soft magnetic ferrites. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions and precursor powders was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a Zeta potential meter, a BET surface analyzer, and a vibrational sample magnetometer (VSM) were used to characterize the precursor sol solutions and the precursor powders. The results showed that these surfactants can improve the dispersion state and Zeta potentials of sol particles and increase the specific surface areas of the precursor powders. Moreover, the precursor powders were composed of MnZn ferrite, and some were amorphous. CTAB was the optimum surfactant and the zeta potential of the sol particles and the specific surface area of the precursor powders named P-0.1CTAB are 10.7 mV and 129.07 m2/g, respectively. In addition, the nano-particles that were made up of the P-0.1CTAB precursor powders had smaller sizes and more uniform particle distributions than the others. The magnetic properties' improvement was attributed to the addition of surfactants, and CTAB is the optimal type. In addition, the novel nano in situ composite method will inspire fresh thinking and investigation into the research of ferrite. [ABSTRACT FROM AUTHOR]

The densified MnZn ferrite ceramics were prepared using the cold sintering process under pressure, with an acetate ethanol solution used as the transient solvent. The effects of the transient solvent, the pressure and annealing temperature on the density, and the micromorphology and magnetic properties of the sintered MnZn ferrites were studied. The densified MnZn ferrite was obtained using the cold sintering process and its relative density reached up to 85.4%. The transient solvent and high pressure are essential to the cold sintering process for MnZn ferrite. The annealing treatment is indispensable in obtaining the sample with the higher density. The relative density was further increased to 97.2% for the sample annealed at 950 °C for 6 h. The increase in the annealing temperature reduces the power loss at high frequencies. [ABSTRACT FROM AUTHOR]

This article proposes a simulation model of single-phase common-mode inductors to evaluate the small-signal characteristic of common-mode inductors when the stray capacitance cancellation method is applied. From the estimated stray capacitance of common-mode inductors, the value of the cancellation capacitors is determined and implemented into the model. Thus, the proposed model can simulate the small-signal characteristic of common-mode inductors with the capacitance cancellation method at the design stage. To validate the proposed model, a comparison between measured and simulated attenuation characteristics of fabricated single-phase common-mode inductors is performed. The comparison result clarifies that the high-frequency attenuation improvement of the capacitance cancellation method is limited for manganese–zinc ferrite-based common-mode inductors due to the steep change of the complex permeability.

In this work, MnZn ferrite nanoparticles with hierarchical morphology were synthesized hydrothermally, and their surface characteristics were improved by the PEGylation process. In vitro MRI studies were also conducted to evaluate the ability of the synthesized nanoparticles as a contrast agent. All results were compared with those obtained for MnZn ferrite nanoparticles with normal structure. Microstructural evaluations showed that in ferrite with hierarchical morphology, the spherical particles with an average size of ~20 nm made a distinctive structure consisting of rows of nanoparticles which is a relatively big assembly like a dandelion. The smaller particle size and dandelion-like morphology led to an increase in specific surface area for the hierarchical structure (~69 m2/g) in comparison to the normal one (~30 m2/g) with an average particle size of ~40 nm. In vitro MRI, cytotoxicity and hemocompatibility assays confirmed the PEG-coated MnZn ferrite nanoparticles with hierarchical structure synthesized in the current study can be considered as an MRI contrast agent. [ABSTRACT FROM AUTHOR]

In this study, MnZn ferrites with added YIG nanoparticles were developed for MHz frequency applications. The effect of the magnetic YIG additive on the power loss, initial permeability, and cutoff frequency of MnZn ferrites was investigated. A small quantity of added YIG effectively reduces the power loss and concurrently increases the initial permeability. Compared to the results for the MnZn ferrite with no added YIG, the optimal MnZn ferrite with 600 ppm added YIG exhibits a reduction in the power loss at 25°C of 56.4% and 36.6% at 1 MHz/50 mT and 3 MHz/10 mT, respectively, and a 13.9% increase in the initial permeability. This sample also exhibits a good stability of the power loss against temperature. The power loss remains below 205 kW/m3 over temperatures ranging from 25 to 140°C. The effect mechanism of YIG addition on the magnetic properties of MnZn ferrites was studied. An analysis based on the equivalent circuit model showed that the reduction in the eddy current loss and power loss mainly results from the increase in the grain boundary resistance caused by the addition of highly resistive YIG. [ABSTRACT FROM AUTHOR]

Current work elaborates magnetic, microstructural, and thermal properties of Mn0.45Zn0.55Fe2O4 ferrite synthesized by the powder metallurgy method. Process parameters have been established to obtain ideal microstructure and magnetic properties at a frequency ranging from 1 kHz to 1000 MHz. Microscopic examinations revealed a uniform spinel structure containing grains size of 12 ± $2 \,\mu \text{m}$ and free of nonmagnetic phases. X-ray diffraction studies evidenced cubic crystal structure for pure spinel MnZn ferrite. The Mn0.45Zn0.55Fe2O4 ferrite exhibits inductance ($A_{L}$) as 5425 nH, initial relative permeability ($\mu _{i}$) as 5877, core loss ($P_{c}$) as 60.422 W/kg, and saturation magnetic polarization ($I_{s}$) as 3.680 kG at a 1000-MHz applied frequency state. Surface coating was applied on toroid shape samples, which revealed a uniform coating thickness ($450 \,\mu \text{m}$) and tenacious appearance of coating layer. Thermal stability of coating was found to be stable up to 150 °C for 6 h. Coating exhibits 35±2 HV hardness and coefficent of friction (CoF) as 0.27, which indicates excellent adherence and high wear resistance of coating. [ABSTRACT FROM AUTHOR]

This study proposes a high-performance magnetic shielding structure composed of MnZn ferrite and mu-metal film. The use of the mu-metal film with a high magnetic permeability restrains the decrease in the magnetic shielding coefficient caused by the magnetic leakage between the gap of magnetic annuli. The 0.1–0.5 mm thickness of mu-metal film prevents the increase of magnetic noise of composite structure. The finite element simulation results show that the magnetic shielding coefficient and magnetic noise are almost unchanged with the increase in the gap width. Compared with conventional ferrite magnetic shields with multiple annuli structures under the gap width of 0.5 mm, the radial shielding coefficient increases by 13.2%, and the magnetic noise decreases by 21%. The axial shielding coefficient increases by 22.3 times. Experiments verify the simulation results of the shielding coefficient of the combined magnetic shield. The shielding coefficient of the combined magnetic shield is 16.5%. It is 91.3% higher than the conventional ferrite magnetic shield. The main difference is observed between the actual and simulated relative permeability of mu-metal films. The combined magnetic shielding proposed in this study is of great significance to further promote the performance of atomic sensors sensitive to magnetic field. [ABSTRACT FROM AUTHOR]

By experiment we evaluated the longitudinal magnetostriction on cylindrical samples of MnZn ferrite. Starting from the idea that the magnetostriction phenomenon is closely related to the magnetization phenomenon of the ferromagnetic sample, by plotting the magnetostriction curve it is possible to extract the magnetization curve of the ferromagnetic material and to evaluate the saturation magnetization of the material and the demagnetizing factor of the sample. At the same time, the paper suggests a way to study the dynamics of the movement of the magnetic domain walls in the sample, by examining the resonance curve at each point on the magnetization curve. • Longitudinal dynamic magnetostriction measurements. • Dynamic magnetostriction resonance curve. • Influence of the demagnetizing field. • Estimation of the magnetization curve for a MnZn ferrite. [ABSTRACT FROM AUTHOR]

MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions and precursor powders was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a Zeta potential meter, a BET surface analyzer, and a vibrational sample magnetometer (VSM) were used to characterize the precursor sol solutions and the precursor powders. The results showed that these surfactants can improve the dispersion state and Zeta potentials of sol particles and increase the specific surface areas of the precursor powders. Moreover, the precursor powders were composed of MnZn ferrite, and some were amorphous. CTAB was the optimum surfactant and the zeta potential of the sol particles and the specific surface area of the precursor powders named P-0.1CTAB are 10.7 mV and 129.07 m2/g, respectively. In addition, the nano-particles that were made up of the P-0.1CTAB precursor powders had smaller sizes and more uniform particle distributions than the others. The magnetic properties’ improvement was attributed to the addition of surfactants, and CTAB is the optimal type. In addition, the novel nano in situ composite method will inspire fresh thinking and investigation into the research of ferrite.

Using molten salt reactions, Ti oxide coatings were successfully deposited on MnZn ferrite in a NaCl–KCl–K2TiF6 melt. The film formed on the surface of MnZn ferrite had a thickness of up to 20 μm and was composed of Ti oxides. The electric conductivity of the coatings was contributed to by the component Ti2O3 and depended on the concentration of Ti2O3 in the film. When the Ti2O3 content in the film increased, the surface resistance dropped to the order of 10−1 Ω/□. The conductive film had the potential to be welded to the metal electrode, thus confirming that the molten salt reaction method could be used as a pre-treatment to realize the metallization of MnZn ferrite. [ABSTRACT FROM AUTHOR]

In this work, MnZn ferrite nanoparticles with hierarchical morphology were synthesized hydrothermally, and their surface characteristics were improved by the PEGylation process. In vitro MRI studies were also conducted to evaluate the ability of the synthesized nanoparticles as a contrast agent. All results were compared with those obtained for MnZn ferrite nanoparticles with normal structure. Microstructural evaluations showed that in ferrite with hierarchical morphology, the spherical particles with an average size of ~20 nm made a distinctive structure consisting of rows of nanoparticles which is a relatively big assembly like a dandelion. The smaller particle size and dandelion-like morphology led to an increase in specific surface area for the hierarchical structure (~69 m2/g) in comparison to the normal one (~30 m2/g) with an average particle size of ~40 nm. In vitro MRI, cytotoxicity and hemocompatibility assays confirmed the PEG-coated MnZn ferrite nanoparticles with hierarchical structure synthesized in the current study can be considered as an MRI contrast agent.

A novel g-C3N4 doped Mn-Zn ferrite composite is prepared by self-assembly method, and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic performance of g-C3N4 doped Mn Zn ferrite composite photocatalyst is studied by the degradation effect of Rhodamine B under visible light. The results show that the photocatalytic activity of g-C3N4 doped Mn-Zn ferrite (2:3) is higher than that of Mn-Zn ferrite and g-C3N4 single components. 0.5g/L sample degrades 96.0% rhodamine B in the solution after 210 minutes of photoreaction. The g-C3N4 doped Mn-Zn ferrite photocatalyst possesses characteristics of strong magnetic property and recyclability. After five times of photocatalytic experiments, the degradation rate of g-C3N4 doped Mn-Zn ferrite photocatalyst is still more than 90%, Thus it is provided with good application prospect in the degradation of environmental pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Analysis of comprehensive magnetic noise in multilayer magnetic shielding system for highly sensitive miniaturized atomic sensors. • A comprehensive multilayer magnetic noise calculation model of the magnetic shielding system of the SERF gyroscope. • Structure design and performance testing of the magnetic shielding system of the SERF gyroscope. The multilayer magnetic shielding system is widely used in atomic sensors. However, for miniaturized atomic sensors with volume limitations, such as spin-exchange relaxation-free (SERF) gyroscopes, the remaining environmental magnetic interference and mu-metal magnetic noise will affect the sensitivity of atomic sensors. In this study, we establish a comprehensive magnetic noise calculation model for the magnetic shielding system of a SERF gyroscope, which considers the influence of the environmental magnetic noise on the magnetic shielding and the coupling effect between different layers. For suppressing magnetic noise of the magnetic shielding system, the property of different ferrites was measured and compared, then the particle swarm optimization is applied to design the magnetic shielding structure. Finally, the experimental device is established for measuring performances of the magnetic shielding system per and post optimization. By comparison, radial and axial magnetic noise post optimization are decreased by 37% and 22%, respectively. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between filter inductor impedance and dimensional resonance of MnZn ferrite. Experimental results clarify that multiple factors affect inductor impedance resonances. These can be classified into three factors: the inherent characteristics of a magnetic material, self-resonance due to winding stray capacitance, and winding that acts as a distributed constant line. Next, based on the measurement results, the dimensional dependencies of complex permeabilities (dimensional resonance) and the influence of dimensional resonance on inductor impedance are discussed in detail. Finally, this study verifies that the influence of dimensional resonance on complex permeability can be mitigated, and filter inductor impedance can be increased in the high frequency range by core lamination. All experiments are performed using off-the-shelf magnetic core products. [ABSTRACT FROM AUTHOR]

MnZn power ferrites are technologically important for miniaturization and efficiency of electronic devices. It is of practical significance to obtain high working frequency and temperature in the MnZn ferrites. In this study, MnZn ferrites capable of working above 1 MHz and 80 °C have been successfully prepared by Nb 2 O 5 and TiO 2 doping. Nb 2 O 5 promotes the densification process during sintering and exists as a resistive layer in the grain boundary region, leading to improved permeability and power losses. TiO 2 doping results in the formation of localized Ti4+-Fe2+ pairs and offers extra cation vacancies for Nb5+ diffusion, which further enhances the effect of Nb 2 O 5. The sample doped with 250 ppm of Nb 2 O 5 and 2500 ppm of TiO 2 presents optimal magnetic properties with the lowest power loss value of 394 kW/m3 at 1 MHz and 80 °C , along with an initial permeability of 1510, thus, serving as a good candidate for MHz, high-temperature and high-permeability power applications. [ABSTRACT FROM AUTHOR]

• Monodomain MnZn soft magnetic ferrite is successfully obtained by SPS technology. • The high-frequency performance is improved by domain rotation in SPS-sintered ferrite. • The power loss at 20 MHz is firstly reported based on homemade testing system. MnZn soft magnetic ferrites are essential materials for energy conversion in power electronics. The rapid development of miniaturized and energy-saving electronics has put forth an urgent need for high-frequency MnZn ferrites. However, the current MnZn ferrites suffer from a rapid decline of permeability and a drastic increase in power loss at frequencies above 5 MHz, which severely limits their use in high-frequency power electronics. In this study, the Spark Plasma Sintering (SPS) technology was used to prepare high-frequency MnZn ferrites. Compared to samples prepared by traditional solid-state sintering, SPS ferrite exhibits superior high-frequency properties with cut-off frequency of 57 MHz, and a power loss of 169.6 kW/m3 at 20 MHz. The improved high-frequency performance is due to the monodomain structure which is induced by grain refinement via spark plasma sintering. This study presents an effective method for manufacturing high-frequency soft magnetic ferrite and will promote the development of high-performance power electronics. [ABSTRACT FROM AUTHOR]

• Mn x Zn 1-x Fe 2 O 4 (x = 0.3, 0.5, 0.7) nanofibers were prepared by the solvothermal reaction and used as reinforcement phase to synthesize the corresponding three types of homogeneous-fiber-reinforced MnZn ferrite materials. • The effects of diverse Mn x Zn 1-x Fe 2 O 4 nanofibers on the structures and magnetic as well as mechanical properties such as effective permeability, magnetic loss, and Vickers hardness of MnZn ferrite materials were investigated systematically. • The homogeneous-fiber-reinforced MnZn ferrite materials had denser crystal structure, excellent magnetic and mechanical properties. • The homogeneous-fiber-reinforced MnZn ferrite materials exhibited better magnetic and mechanical properties as the Mn content of Mn x Zn 1-x Fe 2 O 4 nanofibers increased from x = 0.3 to 0.7. Mn x Zn 1-x Fe 2 O 4 (x = 0.3, 0.5, 0.7) nanofibers were prepared by the solvothermal reaction and used as reinforcement phase to synthesize the corresponding three types of homogeneous-fiber-reinforced MnZn ferrite materials. The dependence of composition, morphology, size, and property of Mn x Zn 1-x Fe 2 O 4 nanofibers on the Mn content was studied. Results demonstrated that Mn x Zn 1-x Fe 2 O 4 nanofibers had uniform 1D fibrous structure, smooth surface, and large aspect ratio, which varied in sizes and arrangements by controlling the ratios of Mn2+ to Zn2+. The lattice parameter gradually decreased and the saturation magnetization (Ms) increased with the Mn content of Mn x Zn 1-x Fe 2 O 4 nanofibers increasing from x = 0.3 to 0.7. Meanwhile, the effects of diverse Mn x Zn 1-x Fe 2 O 4 nanofibers on the structures, magnetic and mechanical properties such as magnetic hysteresis loop, effective permeability, magnetic loss, and Vickers hardness of MnZn ferrite materials were also investigated systematically. Results indicated that the homogeneous-fiber-reinforced MnZn ferrite materials had denser crystal structure, higher strength, and stability, sothat they possessed excellent magnetic and mechanical properties of high Ms , high permeability, low loss, and high hardness. When the Mn content of Mn x Zn 1-x Fe 2 O 4 nanofibers increased from x = 0.3 to 0.7, the homogeneous-fiber-reinforced MnZn ferrite materials exhibited better magnetic and mechanical properties due to the finer size and superior property of the corresponding Mn x Zn 1-x Fe 2 O 4 nanofibers. [ABSTRACT FROM AUTHOR]

In a proton therapy system based on cyclotrons, a kicker magnet is an essential equipment to perform fast beam switch within 100 μ s level during energy modulation and spot scanning procedures. This paper gives a systematic view related to the design and technical considerations of a fast kicker applied to HUST-PTF. From the layout and physical requirement of the kicker, a comparative study on the static/dynamic magnetic field with two type of core materials is performed, and a MnZn ferrite core is chosen finally. Technical considerations including the structure design, the topology design of the power supply, and the method for dynamic field measurement are introduced as well. [ABSTRACT FROM AUTHOR]

BACKGROUND: The accumulation of unwanted microorganisms on wetted surfaces, leading to surface damage and contamination, is a common and significant global issue. RESULTS: Herein, we report a novel technique where the growth of microorganisms can be readily controlled by coating the surfaces with a polydimethylsiloxane (PDMS)/Mn0.8Zn0.2Fe2O4 (manganese‐zinc ferrite) nanocomposite followed by applying alternating magnetic field (AMF). The PDMS/MnZn ferrite nanocomposite is light weight and thermally stable (up to ∼ 330 °C) that can form a flexible coating. PDMS also provides hydrophobicity, which is further enhanced by the addition of Mn and Zn. The improved hydrophobicity makes the coated surface less susceptible to biofilm formation. When external AMF was applied to nanocomposites containing various MnZn ferrite nanoparticle loads of 10%, 20% and 30%, the temperature of the surface of nanocomposites reached to 80, 120 and 160 °C, respectively. Successful biofilm deactivation was achieved by heating the nanocomposites via AMF application, as shown in the biofilm test where up to ∼ 70% of the Pseudomonas aeruginosa PAO1 biofilm cells were killed when the AMF was applied for 20 min to the nanocomposites containing 30% nanoparticles. CONCLUSION: Coating the surface with PDMS/MnZn ferrite nanocomposites followed by applying external AMF can be an effective way to remove biofilm remotely in a wide range of applications. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel in-situ method to measure complex magnetic permeability (CMP) based on the magnetic shielding mechanism is presented. • By measuring the magnetic field at the center of shielding, the effective CMP of a large dimensional ferrite shielding can be determined. • The addition of Co significantly improved the thermal stability of CMP by 6.62 times and reduce the magnetic noise. • This method ensures a real-time observation of CMP and magnetic noise under different temperatures. Magnetic shielding made of low noise ferrite materials is used in many ultra-sensitive measurements. The complex magnetic permeability (CMP) of ferrites directly affects the magnetic shielding performance, so the measurement of CMP is particularly important. Conventional measurements omit the effects of temperature on ferrites' magnetic properties and can only measure samples with specific shapes. Here a novel measurement method of CMP based on the magnetic shielding mechanism is presented. By in-situ measuring the magnetic field, the effective CMP of large dimensional ferrite shielding can be determined. Also, the intrinsic magnetic noise of a MnZn ferrite shielding was observed using the proposed method. Using the finite elements method (FEM), we identified the influencing factors of air gap in the CMP measurements. We also analyzed the influence of element doping on the thermal stability of CMP. This study ensures a real-time observation of CMP and magnetic noise under different temperatures. [ABSTRACT FROM AUTHOR]

In this paper, PEG6000 was used as a surfactant to prevent the MnZn ferrite nanoparticles from aggregation. Introduction of PEG6000 didn’t affect structure of the products, but modified their dispersion state and decreased their particle size. Furthermore, saturated magnetization of the MnZn ferrite nanoparticles increased with an increase in the PEG6000 content, and presented the maximum of 110.3 emu/g at the PEG6000 content of 0.006 mol/l. This value is about 40% higher than that without any PEG6000, and almost the highest one reported to date for the MnZn ferrite nanoparticles. Hence the obtained results proved that the PEG6000 was a powerful surfactant to improve magnetic properties of the MnZn ferrite nanoparticles. [ABSTRACT FROM AUTHOR]

Nanosized MnZn ferrite particles, with narrow size distribution, regular morphology and high saturation magnetization have been synthesized via a modified hydrothermal method. This modified hydrothermal method involves a chemical co-precipitation of hydroxides under a vacuum condition using potassium hydroxide as precipitating agent, followed by a separate hydrothermal process. The microstructure and magnetic properties of the synthesized nanoparticles were investigated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The effects of different synthesis conditions (excess ratio of precipitating agent and hydrothermal reaction time) on the microstructure and magnetic properties of the as-synthesized nanoparticles were discussed. The magnetic measurements indicated that the obtained samples were superparamagnetic in nature at room temperature. Moreover, the MnZn ferrite nanoparticles with excellent magnetic performance could be synthesized at 180 °C for a short reaction time (3 h). [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

MnZnFeO nanoparticles with improved saturation magnetization were prepared by a modified hydrothermal method. This method involves a chemical co-precipitation of hydroxides under a vacuum condition using potassium hydroxide as a precipitating agent, followed by a separate hydrothermal process. To understand the advantages of the modified hydrothermal method proposed above, a sample having identical stoichiometry was prepared by conventional hydrothermal method, during which the preparation of precursor was conducted in an open system. The samples were characterized by XRD, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and TEM. The magnetic property was tested by vibrating sample magnetometer (VSM). XPS results show that the Mn cations of the nanoparticles prepared by modified hydrothermal method have lower average valence. The MnZn ferrite nanoparticles prepared by modified hydrothermal method have smaller diameter (16.1 nm, calculated by XRD) and higher room temperature saturation magnetization, 80 emu/g, which is even better than the reported value. The saturation magnetization of the particles prepared by modified hydrothermal method is 1.6 times of the particles prepared by conventional hydrothermal method. [ABSTRACT FROM AUTHOR]

The complex dielectric permittivity (ε) and magnetic permeability (µ) of Radar Absorbing Materials (RAM) based on magnetic particles (MnZn ferrite particles) embedded in a dielectric matrix (silicon rubber) have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of MnZn ferrite-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the evaluated frequency range is analyzed. In a general way, the results show ε' parameter presenting more significant variation among the evaluated parameters (ε", µ", µ'). The comparison of dielectric and magnetic loss tangents (ε"/ε' and µ"/µ', respectively) shows more clearly the variation of both parameters (ε and µ) according to the frequency. It is also observed that higher MnZn ferrite content fractions favor both dielectric and magnetic loss tangents.

In this study, properties of soft-magnetic manganese zinc ferrite manufactured by powder injection moulding - PIM technology were presented. A powder consisting of Mn1- xZnxFe2O4 with small addition of hematite □-Fe2O3 was mixed with an organic binder (wax and thermoplastic) to form ferrite feedstock. The ferrite feedstock was injected in a mould with a cavity shaped like a small cylinder with a hole on the main axis. Injection moulded samples were then solvent, thermally debinded and sintered in air atmosphere. Structure of sintered sample was characterized using X-ray diffractometry, scanning electron microscopy and thermomagnetic measurements. Magnetic properties were measured by hysteresis graph at different frequencies up to 1 kHz. Sintered sample contains a mixture of two phases Mn0.6Zn0.4Fe2O4 (68 wt. %) and α-Fe2O3 (32 wt. %). The Curie temperature is TC ≈ 220°C for the green sample but after the heating up to 470°C, TC increase up to about 300°C. The high increase of normalized magnetic permeability of about 800 % was observed due to melting and burning of binder. The hysteresis loop of sintered MnZn ferrite toroidal cores has an R-shape with saturation of 0.44 T and remanence ratio of 0.49. The low value of coercivity (only 47 A/m) was related to the presence of α-Fe2O3 crystalline phase and attained already optimum density (ρ ≈ 4.8 g/cm³) i.e. observed low level of porosity. Attained relative magnetic permeability μr ≈ 2000 as well as power losses Ps ≈ 21 W/kg for sintered sample (at 1 kHz; 0.39 T) is in agreement with the MnZn ferrite commercial samples. [Projekat Ministarstva nauke Republike Srbije, br. OI 172057]

AbstractMnZnFe2O4ferrite nanoparticles were prepared by co-precipitation method using a microwave heating system at temperature of 100 °C. X-ray diffraction reveals the samples as prepared are pure ferrite nanocrystalline phase, transmission electron microscopy image analysis shows particles are in agglomeration state with an average size of about 10 nm, furthermore, crystal size of samples are increased with longer microwave heating.

[Display omitted] • Cementitious composites with good EM wave absorption performance are prepared. • Iron powder improves the EM attenuation of the composite. • Graphite can decrease the minimum reflection loss of the cementitious composite. • The EM wave absorpton mechanism of the tested composites is discussed. Long-term EM radiation seriously affects human physical and mental health. MnZn ferrite can improve the microwave absorbing property of cementitious composites, while obvious shortcomings are narrow effective bandwidth and large thickness. In this work, the intensified effects of metallic iron and graphite powders addition on the magnetic properties, impedance matching, EM wave attenuation, and reflection loss (RL) of cementitious composites containing MnZn ferrite were investigated by VSM and VNA. The phase composition, microstructure, and hydration of the composites were analysed by XRD, XPS, SEM–EDS, and FTIR analyses to explore the relationship between the physicochemical properties and EM properties. The favorable EM wave absorption of composites lies in the magnetic loss and dielectric loss with the addition of iron and graphite powder. MnZn ferrite and iron powder addition can effectively improve the dissipation of electric energy and magnetic energy, and reduce the "superior" thickness range (STR) of the composites. 3% iron powder addition can decrease the STR from over 17.3 mm to 9.4–16.3 mm. Taking the thickness of 11.5 mm as an example, the minimum RL and the mean RL of the composite were reduced by 101.3% and 13.2%, respectively, while the effective bandwidth (RL < − 10 dB) was increased from 1.78 GHz to 2.61 GHz. 3% graphite addition decreased the minimum RL of the composite containing both MnZn ferrite and iron powder from −35.3 dB to −43.9 dB at a thickness of 11.5 mm. Meanwhile, the mechanical strength of cementitious composites is sufficient to satisfy the requirements in most building applications. [ABSTRACT FROM AUTHOR]

The conversion of electromagnetic energy into heat by nanomagnets has the potential to be a powerful, non-invasive technique for cancer therapy by hyperthermia and hyperthermia-based drug release, while temperature controllability and targeted heating are challenges to developing applications of such magnetic inductive hyperthermia. This study was designed to control the hyperthermia position and area using a combination of alternating current (AC) and a static magnetic field. MnZn ferrite (MZF) nanoparticles which exhibited excellent hyperthermia properties were first prepared and characterized as an inductive heating mediator. We built model static magnetic fields simply using a pair of permanent magnets and studied the static magnetic field distributions by measurements and numerical simulations. The influence of the transverse static magnetic fields on hyperthermia properties was then investigated on MZF magnetic fluid, gel phantoms and SMMC-7721 cells in vitro. The results showed a static magnetic field can inhibit the temperature rise of MZF nanoparticles in an AC magnetic field. But in the uneven static magnetic field formed by a magnet pair with repelling poles face-to-face, the heating area can be restricted in a central low static field; meanwhile the side effects of hyperthermia can be reduced by a surrounding high static field. As a result we can position the hyperthermia area, protect the non-therapeutic area, and reduce the side effects just by using a well-designed combination of AC and static field. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Single-phase nanoparticles of MnZnFe O (MZF) with improved magnetic properties were prepared from the precursor (formed by chemical route) by microwave processing technique at 500 C in only 3 min. Crystallographically, these were found to be of spinel phase. Using Debye-Scherrer formula, the particle size of conventionally sintered powder is estimated to be about 20 nm, whereas that of microwave processed is nearly 50 nm with improved grain size. The field emission scanning electron (FESEM) and transmission electron (TEM) micrographs revealed the particles in microwave-processed samples to be spherical in shape and confirmed the sample size (to be nearly 50 nm). Room temperature magnetization measurement of conventionally sintered samples (by vibrating sample magnetometer (VSM)) showed their superparamagnetic nature with saturation magnetization of nearly 19 emu/g. The microwave-processed samples showed improved saturation magnetization of nearly 36 emu/g, which is even better than the reported value. [ABSTRACT FROM AUTHOR]

MnZn ferrites are widely used as core materials in electronic applications. However, few studies on fabricated MnZn ferrites microcomponents are available in this paper. To address this issue, a novel fields-activated microforming and sintering technology (micro-FAST) was introduced for the fabrication of MnZn ferrites microparts. The experimental results show that micro-FAST is an efficient process, which has lower energy consumption and little impact on the environment as a result of directly forming the component from loose powders. More interestingly, MnZn ferrite powders with a composition of Zn0.8Mn0.2Fe2O4(wt.%) can be sintered at low temperature without much compromise of the final quality of microparts formed by micro-FAST. To analyze the sintering mechanism, in this paper, the sintering thermodynamics of micro-FAST for the fabrication of Φ 1.0 mm × 1.0 mm sized cylindrical bulk ferrite has been studied. The results show that the sintering energy of micro-FAST for MnZn ferrite powder comes from three sources: 1) heat exchange with die and punches; 2) alternating electric field; and 3) alternating magnetic field. These results being in correspondence with the analytical results of computer simulation. [ABSTRACT FROM AUTHOR]

Samples of manganese-zinc (MnZn) ferrites were successfully prepared by hydrothermal syntheses using different compositions of the reactive system (HO):(EG) ( x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0), where EG = ethylene glycol. The samples were fully investigated by powder X-ray diffraction, Fourier transform infrared spectroscopy for both liquid and solid specimens, Mössbauer spectroscopy, vibrating sample magnetometer, and transmission electron microscopy. All the MnZn ferrites presented spinel phase and average particle diameters between 3.1 and 12.1 nm. The increase in the x values results in a decrease in the particle sizes. The FTIR spectra performed in liquid phase showed significant interaction between EG and metallic precursors used in the synthesis. Magnetic features as for instance saturation magnetization ( M) also decreases upon increasing the x values. In addition, all synthesized samples exhibited a superparamagnetic character at room temperature. The experimental methodology presented in this work is used to obtain superparamagnetic nanoparticles with controlled size (smaller than 13 nm) and morphology. [ABSTRACT FROM AUTHOR]

Abstract: MnZn ferrite nanoparticles have been synthesized by self-propagating high temperature synthesis (SHS) and sol-gel autocombustion techniques. The crystallite size, microstructure and magnetic properties were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) methods. The results showed that single phase manganese ferrite could be achieved directly without any post calcination. However, the crystallite size of the sol-gel autocombusted sample (44nm) was finer than that of the SHS (57nm). The SHS synthesized MnZn ferrite with the larger crystallite size exhibited the larger magnetization of 50.6emu/g than that of 20.9emu/g for the sol gel autocombusted nanoparticles, despite of its more structure inversity. [Copyright &y& Elsevier]

Abstract: MnZn ferrite nanoparticles have been synthesized by a sol–gel autocombustion technique with different pHs of 0, 5 and 7 and different citric acid to metal nitrate (CA/MN) molar ratios of 0.25, 0.5 and 1. The crystallite size, microstructure and magnetic properties were studied using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry methods. The results showed that the single phase MnZn ferrite could be achieved directly without any post-calcination using pH of 7 and CA/MN molar ratio of 0.5. MnZn ferrite nanoparticles prepared by pH=7 and CA/MN=0.5 with the crystallite size of 39nm exhibited saturation magnetization of 20.9emu/g and coercivity of 44Oe. [Copyright &y& Elsevier]

MnZn power ferrites with a composition of MnZnFeCoO were prepared by conventional ceramic technique. The samples were sintered in a computer-driven furnace at 1320 °C for 4 h. Then the influences of Co-substitution on the crystalline structure, microstructure and the magnetic properties of MnZn power ferrite were studied. It shows that Co-substitution has not changed the structure of MnZn ferrite, but improved the crystallization. With the increase of Co substitution content, Co ions firstly replace Mn ions and then replace Fe ions. And at room temperature, the initial permeability increases with the increase of Co-substitution content. Co-substitution can also reduce the porosity and the power loss. In addition, the corresponding temperature of the minimum power loss shifts to a lower temperature. [ABSTRACT FROM AUTHOR]