Mn-Zn Ferrite Particles Research Articles

Long-distance heat transport based on temperature-dependent magnetization of magnetic fluids

Mn-Zn ferrite-based magnetic fluid is temperature-sensitive. Because of the low Curie temperature of Mn-Zn ferrite particles, magnetization is dramatically attenuated as the temperature rises. This temperature-dependent magnetization can be used to transport heat by magnetically driving a fluid via the application of a non-uniform magnetic field and heat. A potential application of this scheme is long-distance heat transport without the use of mechanical pumps. In the present work, a miniaturized magnetically-driven heat transport device with an inner diameter of 𝜙1.54 mm and a flow path length of 1,500 to 6,000 mm was fabricated. The influence of flow path length on the flow rate induced by the magnetic body force was investigated experimentally and theoretically. Although the flow rate decreased with increasing flow path length due to friction loss, the driving pressure increased with rising heater temperature because of the temperature-dependent magnetization. The influence of flow path length on the driving pressure is relatively insignificant. An increase in the flow path length leads to effects that both attenuate and enhance the driving pressure. Substantial long-distance (6,000 mm) heat transport was realized by applying a non-uniform magnetic field and heat.

Green synthesis of a novel Mn–Zn ferrite/biochar composite from waste batteries and pine sawdust for Pb2+ removal

Magnetic ferrite/biochar composites are a kind of promising adsorbents due to their high adsorption efficiency and facile magnetic separation; however, their synthesis is associated with high cost and secondary environmental impacts. In this study, a novel Mn–Zn ferrite/biochar composite (MZF-BC) is synthesized via a green two-step biocheaching and hydrothermal method using waste batteries and pine sawdust. Characterization results indicate that the introduced Mn–Zn ferrite particles are successfully embedded and coated on biochar (BC), and synthesized MZF-BC50 with 50% BC content exhibits best performance with a specific surface area of 138.5 m2 g−1, the saturation magnetization of 27.5 emu g−1 and CEC value of 53.2 mmol 100 g−1. The maximum adsorption capacity of Pb2+ is 99.5 mg g−1 based on the Langmuir sorption isotherm study at 298 K, and pseudo-second-order model accurately describes the adsorption process. Regeneration test suggests that MZF-BC50 can be efficiently reused for 6 cycles. In addition, it exhibits a good selective Pb2+ and Cd2+ removal performance in lead-acid battery wastewater. The results illustrate that this newly developed material has low cost and rapid remediation of Pb2+ as good application potential.

Electromagnetic absorption behaviour of ferrite loaded three phase carbon fabric composites

This article investigates the electromagnetic absorption behaviours of carbon helical yarn fabric reinforced composites and manganese–zinc (Mn–Zn) ferrite particles loaded 3 phase fabric composites. A carbon helical yarn having stainless steel core was prepared and made into single jersey knitted fabric. The composite was prepared by sandwiching a fabric with polypropylene films and thermal pressed. The absorption values of helical yarn fabric composite was observed to be less in the C band region (4–8 GHz). For improving the absorption coefficients of composite, Mn–Zn ferrite particles were dispersed in the polypropylene (PP) composite. The ferrite loaded PP composites exhibited better permittivity and permeability values, hence the absorption loss of the composite was improved. The helical yarn fabric reinforced with Mn–Zn ferrite/PP composite showed larger absorption coefficients than virgin PP/fabric composite. The change in thermal stability and particle size distribution in the Mn–Zn ferrite/PP composite was also analyzed. At higher ferrite concentration, bimodal particle distribution was observed which increased the conductivity and shielding effectiveness (SE) of the composite. In addition, complex permittivity value was also increased for higher incident frequency (4–8 GHz). As the ferrite content increases, the dielectric loss and magnetic permeability of PP/ferrite increases due to increased magnetic loss. Hence, ferrite loaded PP composite showed the total SE of −14.2 dB with the absorption coefficients of 0.717. The S1C7 fabric composite having ferrite dispersion showed the better absorption loss and lower reflection coefficient of 14.2 dB and 0.345 respectively compared to virgin PP/helical yarn fabric composite. The increasing ferrite content (45 wt%) improved the absorption loss and total SE. Though, ferrite based fabric composite exhibits moderate absorptive shielding, it can be used as shielding panels in the electronic industries.

Electric properties of MnZn ferrite/polyaniline composites: the implication of polyaniline morphology

(Di)electric properties of MnZn ferrite particles coated by conductive (emeraldine salt) and non-conductive (emeraldine base) forms of PANi were measured and discussed in relation to properties of individual components of such composite. The electric response in a wide frequency (0.1 Hz–10 MHz) and temperature (−150 to 100 °C) range was determined. Recorded relaxation processes were identified as a result of hopping charge carriers, which either only polarize or give rise to DC conductivity. Temperature dependence of conductivity modelled by variable range hopping model indicated different system dimensionality: 3D in PANi bulk and 1D in PANi film, that is result of PANi morphology variation. AC conductivity frequency spectra were well approximated by power law model, and temperature evolution of its exponent was related to the type of charge involved in the charge transport. Altogether, the overlayer of conductive PANi increases by two orders of magnitude the electrical conductivity of ferrite/PANi composite compared to pristine ferrite, whereas non-conductive PANi reduced it by three orders of magnitude. Therefore, the electrical properties of ferrite/PANi composites are determined by electrical properties of PANi, which in turn depend upon mesoscale charge transport in PANi.

Effects of a slurry's particle dispersion and flocculation state on spray-dried granule morphology

Abstract In this study, we investigated the relationship between slurry and spray-dried granule properties. Various slurries were prepared using different sizes of Mn-Zn ferrite particles and evaluated using flow curve and adsorbed dispersant amount measurements and sedimentation tests. Spray-dried granules were evaluated using morphology observations, density and strength measurements, and compression tests. The results demonstrated that a slurry with a relatively high particle dispersion could produce a solid granule with a relatively low density during spray-drying. The results further suggested that the change in a slurry's particle dispersion and flocculation state during drying strongly influenced the granule morphology.

Synthesis and characterization of nanosized MnZn ferrites via a modified hydrothermal method

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 (3h).

Structure and magnetic properties of ZnO coated MnZn ferrite nanoparticles

A comparative study of structural and magnetic properties of MnZn spinel ferrite (SF) and ZnO coated MnZn ferrite (ZF) nanoparticles (NPs) has been carried out. The as-prepared NPs show a single phase cubic spinel structure, with lattice parameter ~8.432Å. However, α-Fe2O3 impurity phase emerge from SF particles when subjected to annealing at 600°C in air. The weight fraction of α-Fe2O3 phase increases with increasing Mn concentration (9% for x=0.2 and 53% for x=0.6). On the other hand in ZF (x=0.2 and 0.4) NPs no trace of impurity phase is observed when annealed at 600°C. The magnetic measurements as a function of field and temperature revealed superparamagnetic like behavior with cluster moment ~104μB in as-prepared particles. The cluster size obtained from the magnetic data corroborates well with that estimated from structural analysis. Present results on ZnO coated MnZn ferrite particles suggest that an interfacial (ZnO@SF) reaction takes place during annealing, which results in formation of Zn-rich ferrite phase in the interface region. This leads to deterioration of magnetic properties even in the absence of α-Fe2O3 impurity phase.

Structure and properties of MnZn ferrite nanoparticles synthesized via sol–gel autocombustion method

MnZn ferrite powder particles were prepared via a sol–gel autocombustion method using nitrates as raw materials. Transmission electron micrographs revealed that the particles were uniform and decentralized with sizes of 20–30 nm. X-ray diffraction patterns showed characteristic features of Mn0.5Zn0.5Fe2O4 ferrite crystals with a nanocrystalline cubic spinel structure and crystallite size of 21.5 nm. The lattice constant determined from the Rietveld refinement was 8.475 A. A saturated magnetic induction intensity of 39.18 emu/g and coercive force of only 18.1 Oe were measured using a quantum design physical property measurement system.

Study of the preparation of NI–Mn–Zn ferrite using spent NI–MH and alkaline Zn–Mn batteries

Magnetic nanoparticles of Ni–Mn–Zn ferrite have been prepared by a sol–gel method making use of spent Ni–MH and Zn–Mn batteries as source materials. Characterization by X-ray diffraction was carried out to study the particle size. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From studies by thermogravimetry and differential scanning calorimetry, crystallization occurred at temperatures above 560°C. The magnetic properties of the final products were found to be directly influenced by the average particle size of the product. The Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases.

Effect of Gd3+ ion distribution on structural and magnetic properties in nano-sized Mn–Zn ferrite particles

Nanoparticles of Gd3+ ions doped Mn0.5Zn0.5GdxFe2−xO4 (x=0.1, 0.2, 0.3, 0.4) mixed ferrite were prepared using chemical co-precipitation method. The X-ray diffraction measurements confirmed the formation of a cubic spinel structure. The structural parameters like crystallite size, lattice parameter and strain induced have been calculated. The lattice parameter increases with the increase in Gd3+ ion concentration and shows non linear behaviour. HRTEM investigation confirms the nano size formation of the Gd doped Mn–Zn ferrite nanoparticles. EPR was used to evaluate resonance peak intensity, Lande’s splitting factor (g value), peak to peak line width (ΔHp–p), spin concentration (Ns) and relaxation time (τs). Line width, line intensity, relaxation time and spin concentration increase with Gd3+ ions doping (for x=0.1 to x=0.3) and then decrease for x=0.4, whereas the g value shows the reverse trend for the same composition. IR spectra shows two strong absorption bands at 570cm−1 and 416cm−1 of tetrahedral and octahedral bond stretching respectively in all the samples. IR spectrum also shows that Gd3+ occupies the octahedral B-sites. Magnetic parameters such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) were measured by search coil method. The value of saturation magnetization increases from 29.94emu/gm for x=0.1 to 46.01emu/gm for x=0.4.

Complex permeability and permittivity variation of radar absorbing materials based on MnZn ferrite in microwave frequencies

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.

Conversion of waste Mn–Zn dry battery as efficient nano-adsorbents for hazardous metals removal

A novel technique was successfully developed for manufacturing Mn-Zn ferrite nano-particles by acid dissolution and ferrite processes. The powders of waste dry batteries (PWDBs) were used as starting raw materials because the Mn and Zn content inside the PWDBs is potentially high. Our data showed that the most abundant elements inside PWDBs are manganese (41.0%), oxygen (40.6%), zinc (15.3%), and carbon (3.1%). It was found that proper reductant was critical for dissolution where FeSO4 is essential for spinel ferrite formation. Synthesized Mn-Zn ferrite particles reached their saturation magnetization at 63.8emu/g and were successfully applied for As, Cd, and Pb removal in aqueous solution. Under the conditions of Mn-Zn ferrite 0.005g, volume 10mL, temperature 27°C, and contact time 1h, As, Cd, and Pb removal could reach 99.9, 99.7, and 99.8%, respectively. We demonstrate a novel method that can be applied for transforming WDBs into resource materials. This not only reduces the amount of WDBs, but also supports the concept of waste-battery reusable green-energy policy.

超音波噴霧熱分解法によるナノMn-Znフェライト粒子の作製および磁気特性

Nano-crystalline Mn-Zn ferrite powders (Mn1-xZnxFe2O4, x=0∼1.0) have been prepared by ultrasonic spray pyrolysis method. Mn-Zn ferrite samples sintered at 700°C had the single phase of spinel-type for all of the compositions. The lattice constant decreased with increasing Zn content and followed Vegard's law. Curie temperature linearly decreased from that of MnFe2O4 (x=0) with increasing Zn substitution rate. These results indicate that the Mn-Zn ferrite formed solid solution. The Mn-Zn ferrite particles were found to be in nano-size of 20∼30 nm by scanning electron microscopy. And their crystalline diameters were 15∼30 nm, determined by the use of Scherrer equation for X-ray diffraction peak broadening. Mn0.6Zn0.4Fe2O4 sample had a magnetization value of 48 emu/g, which was lower than that of bulk sample (80 emu/g). This is possibly caused by the existence of a disordered surface region on the nanoparticles, where the crystallographic and magnetic structures are disordered due to the nearly random distribution of cations and the canted spin arrangement.

Nanocrystalline magnetite and Mn–Zn ferrite particles via the polyol process: Synthesis and magnetic properties

Nanocrystalline Fe 3O 4 and Mn–Zn ferrite powders with crystallite sizes of 10 and 7 nm, respectively, and narrow size distribution were synthesized in a triethylene glycol medium. Mn–Zn ferrite particles with crystallite size of 9 and 12 nm were obtained after annealing of the as prepared ferrite particles at 300 and 500 °C, respectively. The saturation magnetization at 5 K of the Mn–Zn ferrite obtained at 300 °C (79 emu g −1) is smaller than that of the bulk material. Hysteresis loop measurements indicate ferrimagnetic behavior at 5 K and superparamagnetic behavior at 295 K. The Mn–Zn ferrite nanocrystals obtained at 500 °C, however, exhibit a smaller M s compared to the ferrite annealed at 300 °C indicating a change in the cation distribution.

Heat Transfer Characteristics of a Thermo-sensitive Magnetic Fluid in Micro-channel

In the present study, the flow characteristics and heat transfer of a thermo-sensitive magnetic fluid, which is a multiphase-flow material, were investigated experimentally. The mini-channels considered herein have a depth of 0.5 mm, with the nominal channel width being equal to five times the depth. The channel device was constructed from a Teflon tube. The operation of the device is based on the thermo-magnetic characteristics of the fluid, a suspension of Mn-Zn ferrite particles in kerosene, the magnetization of which is known to decrease with increasing temperature. The experimental parameters were magnetic force, the position of the magnet, and the temperature of the magnetic fluid. The experimental results indicate that force convection based on the magnetic characteristics of the fluid in the mini-channel exhibits excellent cooling performance. Furthermore, the flow characteristic of the thermo-sensitive magnetic fluid was found to be strongly dependent on the magnetic condition, such as the force and the position.

Fabrication of a Planar Inductor Using a Thick-Film Magnetic Metal Particle/Non-magnetic Material Composite for Micro Power Supply

In a previous study, a thick-film Mn-Zn ferrite particle/polyimide composite material for power inductors was developed using screen printing technique. This composite film enabled us to obtain a thin planar power inductor. However, downsizing of the planar inductor required that Mn-Zn ferrite particles be replaced by other magnetic particles with the higher permeability. In this study, we used two powdery magnetic metals to create a thick-film composite material, and fabricated downsized planar inductors using such composites. When used in a step-down chopper dc-dc converter, the fabricated inductors exhibited electric properties equal to those of competitive ready-made inductors, which are thicker than our planar inductor.

Study on Heat Transfer Characteristics of Thermo-Sensitive Magnetic Fluid in Micro-Channel

In the present study, the flow characteristics and heat transfer of a thermo-sensitive magnetic fluid, which is a multiphase-flow material, were investigated experimentally. Heat transport systems using magnetic fluids have been proposed by several researchers, but miniature devices of this type have not yet been developed. The mini-channels considered herein have a depth of 0.5 mm, with the nominal channel width being five times the width. The channel device was constructed from a Teflon tube. The operation of the device is based on the thermo-magnetic characteristics of the fluid, a suspension of Mn-Zn ferrite particles in kerosene, the magnetization of which is known to decrease with increasing temperature. The experimental parameters were magnetic force, the position of the magnet, and the temperature of the magnetic fluid. The experimental results indicated that force convection based on the magnetic characteristics of the fluid in the mini-channel exhibited excellent cooling performance. In particular, the observed variations in the flow patterns were compared with the results of a boundary layer of the flow velocity in the pipe, which is generally known. Furthermore, it was found that the flow characteristic of the thermo-sensitive magnetic fluid was strongly dependent on the magnetic condition, such as the force and the position.

Application of Magnetic Ferrite Electrodeposition and Copper Chemical Mechanical Planarization for On-Chip Analog Circuitry

AbstractInductors are important components of analog circuit designs, from matching circuitry to passive filters. In this study, the application of electrophoretically deposited nano-ferrite material has been investigated as a technique to increase the inductance of integrated copper planar inductors fabricated using copper plating and chemical mechanical planarization. Sintered Mn-Zn ferrite particles are suspended in a medium of isopropyl alcohol with magnesium nitrate and lanthanum nitrate salts. The transportation of the particles to the substrate surface is assisted by applied electric field and particles adhere to the substrate surface by a glycerol based surfactant. Electrophorectic deposition process forms a self aligned polymeric thin film on the surface of a p-type silicon substrate selectively with respect to copper. This ferrite deposition method yields high selectivity to the inductor coils and patterned silicon substrates compatible with standard silicon technology.

Rapid synthesis of Mn 0.65Zn 0.35Fe 2O 4/SiO 2 homogeneous nanocomposites by modified sol–gel auto-combustion method

MnZn-ferrite/SiO 2 nanocomposites with different silica content were successfully fabricated by a novel modified sol–gel auto-combustion method using citric acid as a chelating agent and tetraethyl orthosilicate (TEOS) as the source of silica matrix. The auto-combustion nature of the dried gel was studied by X-ray diffraction (XRD), Infrared spectra (IR), thermogravimetry (TG) and differential thermal analysis (DTA). Transmission electron microscope (TEM) observation shows that the MnZn-ferrite particles are homogeneously dispersed in silica matrix after auto-combustion of the dried gels. The magnetic properties vary with the silica content. The transition from the ferromagnetic to paramagnetic state is observed by Mössbauer spectra measurement with the increasing silica content. Vibrating sample magnetometer (VSM) shows that the magnetic properties of Mn 0.65Zn 0.35Fe 2O 4/SiO 2 nanocomposites strongly depend on the silica content.

Effects of La3+ doping on MnZn ferrite nanoscale particles synthesized by hydrothermal method

MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The results show that the sample with 0.2% La3+ (mass fraction) or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to 1.2%. TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A · m2 · kg−1) is lower than that of undoped (17.54 A · m2 · kg−1) and it behaves superparamagnetically.