Manganese Zinc Ferrite Research Articles

Study on preparation of manganese–zinc ferrites using spent Zn–Mn batteries

Studies on preparing manganese–zinc ferrites by coprecipitation method using spent Zn–Mn batteries have been carried out to determine the influential factors on preparing process, including coprecipitation pH value, coprecipitation temperature and calcining temperature, etc. Results show that the suitable preparing conditions are: coprecipitation pH value, 7–7.5; copecipitation temperature, 50 °C and calcining temperature, 1100–1150 °C. It also finds that Fe powder is the suitable material to remove Hg existing in spent Zn–Mn batteries completely.

Effect of Nanosized Dopants on the Magnetic Properties of the Low Power Loss Manganese Zinc Ferrite

Effect of Nanosized Dopants on the Magnetic Properties of the Low Power Loss Manganese Zinc Ferrite

Anomalous behavior of the crystallographic and electron states in MnxZnyFezO4 ferrites

The process of structural self-organization in manganese zinc ferrites with arbitrarily varying cationic sublattice composition has been theoretically analyzed and experimentally studied by methods of X-ray diffraction and K-emission spectroscopy. It is shown that there are strong relations between various experimentally determined parameters. These relations possess an extremal character, which is manifested by “grooves” and “ridges” on the (E, θ, I) surfaces. This behavior is explained based on the notions about the electron population of states stabilized due to spontaneous deformation of the crystal structure, which gives rise to a strong coupling effect.

Magnetic behaviour of composites containing polyaniline-coated manganese–zinc ferrite

Polycrystalline manganese–zinc ferrite has been coated with polyaniline (PANI) and embedded into a polyurethane matrix. The complex permeability of the composites was studied in the frequency range 1 MHz–3 GHz. The conductivity of PANI coating was adjusted by controlled protonation with picric acid. Large shifts in the resonance frequency were observed as a function of varying PANI conductivity. The changes in the magnetic properties of the PANI-coated composite material are due to the change of the boundary conditions of the microwave field at the interface between the ferrite particle and polymer matrix. This effect is observed especially when the magnetic anisotropy of ferrite is low.

Preparation and characterization of MnZn–ferrite nanoparticles using reverse micelles

Research on manganese zinc ferrites (MZFO) has undergone a renewal in recent years as advances in synthetic techniques promise smaller grain sizes and corresponding changes in material properties. Current techniques for nanoscale synthesis of ferrites, however, produce a broad distribution of particle sizes, thus limiting the density of compacted materials, and consequently altering coercivity [C. Rath et al., J. Appl. Phys. 91, 2211 (2002)]. To minimize porosity, bulk materials need to be pressed from uniform particles. Wet chemical synthesis performed in reverse micelles, in which pools of water are encased by surfactant molecules in an excess volume of oil, provides the greatest control over size and morphology. During synthesis, surfactant molecules keep particles separated and restrict particle growth. This affords greater control over the size and shape of the particles grown in the micelles and commonly results in highly uniform morphologies [J. P. Chen et al., J. Appl. Phys. 76, 6316 (1994); C. Liu et al., J. Phys. Chem. B. 104, 1141 (2000)]. As a first step, it is necessary to produce pure phase, nanosized ferrite particles, therefore in this study, analysis of the powder of a sample prepared by a reverse micelle technique is compared to a sample prepared by a traditional ceramic method. Future studies will focus on the porosity and subsequent material properties of compacted forms of the pure phase samples.

Quantitative Analysis of Zinc Vaporization from Manganese Zinc Ferrites

Zinc vaporization of Mn‐Zn ferrites was quantitatively characterized in terms of oxygen partial pressure PO2, temperature, grain size and sample geometry. The amount of zinc loss was measured as a function of time at various temperatures by a thermogravimetric method. The weight loss due to irreversible zinc vaporization showed a linear behavior with time and increased exponentially with temperature. The observed weight loss due to zinc evaporation at 1100°C was small, whereas a significant weight change was detected at 1200°C. The weight loss was even greater in a reducing atmosphere (PO2= 5 × 10−5). Below 1300°C, the diffusion of elemental zinc was sufficiently fast to compensate the zinc loss at the interface region, resulting in a linear dependence on time. At temperatures ≥1400°C, the weight change no longer followed the linear dependence and showed a rather parabolic behavior with a concave upward slope. The core shape and the gas flow around ferrite cores were important factors that affected the rate of zinc vaporization, but not the grain size.

The effect of nano-SiO 2 on the magnetic properties of the low power loss manganese–zinc ferrites

The effect of the addition of nano-SiO 2 on the power losses in the manganese–zinc ferrites has been investigated by measuring the magnetic properties and observing the grain boundary structures. The powders of Mn 0.72Zn 0.21Fe 2.07O 4 composition were prepared by using a conventional ceramic powder processing technique. Toroidal cores were sintered at 1340°C for 4 h using a tube furnace with atmosphere controlled by using the equation for equilibrium oxygen partial pressure. The microstructure of grain boundary was observed by AES and SEM. It has been found that the grain boundaries resistivity and magnetic loss are greatly dependent upon the content of nano-SiO 2. There is an optimum content of nano-SiO 2 to produce uniform grain structure and low magnetic loss. The eddy current losses were reduced by the addition of nano-SiO 2. These losses are thought to originate from the additive effect of Si atoms, which are enriched in grain boundaries to form a high resistivity layer and prevent Ca and Nb atoms being incorporated with the spinel lattice.

Preparation and magnetic properties of MgZn and MnZn ferrites

Synthesis of magnesium–zinc [(Mg 0.63Zn 0.37)(Mn 0.1Fe 1.8)O 3.85] and manganese–zinc [(Mn 0.55Zn 0.35Fe 0.1)Fe 2O 4] ferrites by solid-state reaction method is described. Brunauer–Emmett–Teller (BET) surface areas of the ferrite powders used for synthesis were 2.63 m 2/g for magnesium–zinc ferrite and 2.86 m 2/g for manganese–zinc ferrite respectively. The dense sintered bodies of MgZn and MnZn ferrites obtained at 1250–1300 °C were characterized by the presence of Fe 2O 3 particles uniformly dispersed through a cross-section. Saturation magnetization and hysteresis loops of MgZn and MnZn ferrites were measured using a vibrating magnetometer for both powdered and sintered samples. The samples were distinguished by small core losses and small coercive forces characteristic for soft magnetic materials. The hysteresis loops width for powdered materials were of the order of 15–35 Oe, whereas for sintered specimens they were less than 1 Oe. The saturation magnetization for powders were different from that for sintered samples. The microstructure, chemical, and phase analyses of powders and sintered bodies of ferrites were conducted by scanning electron microscopy (SEM), by energy dispersion X-ray spectroscopy (EDS), and X-ray diffraction (XRD).

EFFECTS OF MAGNETIC FIELD ON FRACTURE TOUGHNESS OF MANGANESE–ZINC FERRITE CERAMICS

Effects of magnetic field on the fracture toughness of magnetic ceramics were experimentally investigated by the use of the single-edge-notch-beam (SENB) specimens of three kinds of manganese–zinc ferrite ceramics with different permeability. Results indicate that there is no significant change in the measured fracture toughness of the Manganese-Zinc Ferrite ceramics in the presence of the magnetic field. Furthermore, the crack lengths caused by the Vickers' indentation on the manganese–zinc ferrite ceramics show that the fracture toughness in the magnetic field direction is almost identical to that in the direction perpendicular to the magnetic field. This reveals that the polycrystalline ceramic still exhibits isotropic fracture behavior after magnetization. Finally, a qualitative explanation is given in terms of a small-scale magnetic saturation model.

Effect of Aggregates on the Microstructure in Manganese Zinc Ferrite

To study the effect of aggregates on the microstructure of sintered bodies, Mn-Zn ferrite powders were prepared by an alcoholic dehydration method. Aggregate powders and reground powders were used as seeds and matrices, respectively. The mixing ratios for the aggregate and reground powders were varied with the sintering temperatures. Green densities were measured with changes in forming pressure and they were related to the microstructures of the sintered bodies. The aggregates proved to be capable of acting as seeds for abnormal grain growth. When the green density difference between the aggregate and the matrix was large, the aggregate could become the seed of abnormal grain growth. As the forming pressure increased, the more aggregates became seeds of abnormal grain growth.

Multiedge refinement of extended x-ray-absorption fine structure of manganese zinc ferrite nanoparticles

The structure of nanoparticle manganese zinc ferrites synthesized by a reverse micellar method is determined by analysis of the extended x-ray-absorption fine structure in combination with other techniques. Both empirical and theoretical standards are employed; manganese, zinc, and iron edges are refined simultaneously. It is determined that samples synthesized under similar conditions sometimes exhibit a markedly different distribution of cations between the available sites in the spinel structure; this in turn causes significant differences in the magnetic properties of the samples. In addition, it is found that the mean-square displacements for manganese-oxygen bonds are consistently higher than for zinc-oxygen bonds, perhaps due to the presence of manganese ions of more than one valence.

Use of multiple-edge refinement of extended x-ray absorption fine structure to determine site occupancy in mixed ferrite nanoparticles

The site occupancy of manganese zinc ferrite (MZFO) nanoparticles is determined by a multiple-edge refinement of the extended x-ray absorption fine structure of the manganese, zinc, and iron absorption edges. The MZFO nanoparticles are generated by a reverse micellar synthetic route and compared to a ceramic standard. The simultaneous fitting of multiple absorption edges to a constrained model is found to yield site occupancies accurate to within eight percentage points.

Aggregate and necking force in Mn–Zn ferrite

An experimental technique is proposed for evaluating the strength of aggregates during powder compaction. The technique is based on the interpretation of compaction pressure vs. green density. A Rumpf's equation was correlated with the equation suggested by Duckworth. Neck strength between primary particles, H=( σ 0 πa 2 e − Bp )/((1− p) K) in manganese zinc ferrite aggregate is thought to be 4.05×10 −5 N, with reference value of σ 0. Manganese zinc ferrite decomposed from the precipitates of alcoholic dehydration was fractured at 300 MPa of the compaction pressure. From this, H was calculated as 5.03×10 −5 N.

A static hysteresis model for power ferrites

Basso and Bertotti's physics-based, yet simple, static hysteresis model is brought to the power electronic community as an alternative for simulation of magnetic components embedded in a power electronic converter. The model is reviewed and its equations cast in application/simulation-oriented forms. It is then revised to better characterize the very soft saturation behavior of commercial power manganese-zinc (MnZn) ferrites. The procedures to extract the model parameters from voltage and current measurements are described. The improved models have been verified against experimental data for major and minor hysteresis loops of three commercial power ferrites.

Ultrasonic investigation on mixed manganese–zinc ferrite

The ultrasonic velocity ( v 1) and attenuation coefficients ( α) have been measured in mixed Mn–Zn ferrites at 2-, 3-, 5- and 10-MHz frequencies by Pulse Echo Overlap (PEO) method. Young's Modulus ( E), isotropic compressibility ( K s), acoustic impedance ( Z) and internal friction ( Q −1) are computed from experimental values of v 1 and α. The variation of measured and computed parameters with change in frequency was reported.

Processability, hardness, and magnetic properties of rubber ferrite composites containing manganese zinc ferrites

Rubber ferrite composites have the unique advantage of mouldability, which is not easily obtainable using ceramic magnetic materials. The incorporation of mixed ferrites in appropriate weight ratios into the rubber matrix not only modifies the dielectric properties of the composite but also imparts magnetic properties to it. Mixed ferrites belonging to the series of Mn(1 -x)Znx Fe2 O4 have been synthesised with different values of x in steps of 0·2, using conventional ceramic processing techniques. Rubber ferrite composites were prepared by the incorporation of these pre-characterised polycrystalline Mn(1 -x)ZnxFe2 O4 ceramics into a natural rubber matrix at different loadings according to a specific recipe. The processability of these elastomers was determined by investigating their cure characteristics. The magnetic properties of the ceramic fillers as well as of the rubber ferrite composites were evaluated and the results were correlated. Studies of the magnetic properties of these rubber ferrite composites indicate that the magnetisation increases with loading of the filler without changing the coercive field. The hardness of these composites shows a steady increase with the loading of the magnetic fillers. The evaluation of hardness and magnetic characteristics indicates that composites with optimum magnetisation and almost minimum stiffness can be achieved with a maximum loading of 120 phr of the filler at x=0 4. From the data on the magnetisation of the composites, a simple relationship connecting the magnetisation of the rubber ferrite composite and the filler was formulated. This can be used to synthesise rubber ferrite composites with predetermined magnetic properties.

Modification of dielectric and mechanical properties of rubber ferrite composites containing manganese zinc ferrite

Spinel ferrites constitute an important class of magnetic materials. Polycrystalline ferrites are a complex system composed of crystallite grain boundaries and pores. Manganese zinc ferrites have resistivities between 0.01 and 10 Ω m. Making composite materials of ferrites with either natural rubber or plastics will modify the electrical properties of ferrites. Composite materials are ideally suited for many modern applications where ceramic materials have some drawbacks. The mouldability and flexibility of these composites find wide use in industrial and other scientific applications. Mixed ferrites belonging to the series Mn (1− x) Zn x Fe 2O 4 (MZF) were synthesized for different ‘ x’ values in steps of 0.2. These pre-characterized ceramic ferrites were then incorporated in a natural rubber matrix. The dielectric properties of the ceramic manganese zinc ferrite and RFC were also studied. A program based on G programming was developed with the aid of LabVIEW package to automate the dielectric measurements. The dielectric permittivity of the RFC were then correlated with that of the corresponding dielectric permittivity of the magnetic filler and matrix by a mixture equation, which helps to tailor properties of the composites.

磁性材料 ＭｎＺｎフェライト薄膜の微細構造に及ぼす熱処理雰囲気および添加物の効果

Manganese zinc ferrite thin films were prepared on quartz substrates buffered by a (00l) oriented ZnO underlayer by conventional rf magnetron sputtering method Mn-Zn-Fe oxide layers deposited on the ZnO underlayers were annealed in various atmospheres at 800°C for 5hours. When the films were annealed either at reduced pressure in air or in N2 gas flow, single phase spinel-type ferrite was formed. Manganese zinc ferrite films annealed in N2 gas flow had excellent soft magnetic characteristics compared with the films annealed at reduced pressure in air because of their remarkable grain growth. Furthermore, Bi2O3 and V2O5 were added for the purpose of inducing crystal grain growth. Manganese zinc ferrite films with Bi2O3 were improved in their saturation magnetization because of their grain growth and good crystallinity. On the other hand, manganese zinc ferrite films with V2O5 showed excellent soft magnetic characteristics, when vanadium of 0.51 at.% was added.

Distortion of a matrix structure and the cluster formation in MnxZnyFezO4 ferrite single crystals

The evolution of the hard and soft modes in the crystal structure of MnxZnyFezO4 manganese-zinc spinel ferrites is investigated theoretically and experimentally (x-ray structure analysis and magnetic measurements). It is shown that tetragonal and rhombohedral distortions of the cubic structure and fluctuations of the soft mode are accompanied by the formation of clusters in the form of quasi-two-dimensional fragments (50–200 and 400–1200 A), which involve families of γ-Mn2O3, γ-Mn3O4, and α-Fe2O3 oxide planes inherently bound to the spinel matrix.

Mathematical formulation for modellingminor and major hysteresis loops of power ferrites

A mathematical formulation that would enable the Basso-Bertotti domain-wall-motion (DWM) model to describe those static hysteresis phenomena that are not necessarily governed by DWM is presented. The motivation for this work has been the need to characterise both the major loop and the minor loops of the power ferrites used in power electronic applications. The key contribution is the introduction of a model parameter mt that defines the transition between low field/minor loops and high field/major loop. The formulation is verified against experimental data of a commercial manganese-zinc (MnZn) ferrite.