Microstructure and magnetic properties of Ni-Zn ferrites doped with MnO_2

To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 does not form a visible second phase in the doping mass fraction range of（0-2.0%）.The average grain size,sintering density and real permeability gradually decrease with the increase of the MnO2 content.And the DC resistivity continuously increases with the increase of MnO2 content.The saturation magnetization（magnetic moment in unit mass） first increases slightly when mass fraction of MnO2 is less than 0.4% MnO2,and then gradually decreases with increasing the MnO2 mass fraction due to the exchange interaction of the cations.When the excitation frequency is less than 1 MHz,the power loss（Pcv） continuously increases with increasing the MnO2 content due to the decrease of average grain size.However,when the excitation frequency exceeds 1 MHz,eddy current loss gradually becomes the predominant contribution to Pcv.And the sample with a higher resistivity favors a lower Pcv,except for the sample with 2.0% MnO2.The sample without additive has the best Pcv when worked at frequencies less than 1 MHz;and the sample with 1.6% MnO2 additive has the best Pcv when worked at frequencies higher than 1 MHz.

Effects of Nd^(3+)on the microstructure and magnetic properties of Ni-Zn ferrites

Ni0.4Zn0.6Fe2-xNdxO4（x = 0-0.07） ferrites doped with different amounts of Nd2O3 were prepared using standard ceramic technique. The samples were uniaxially pressed and sintered at 1250℃ for 4 h in air. The phase structure and microstructure of the samples were investigated using X-ray diffraction and scanning electron microscope, respectively. The complex permeability was measured using the impedance analyzer in the range of 1-100 MHz. The results indicate that with increasing Nd^3＋ content, the relative density and lattice parameter a of the sintered samples increase, whereas the real part of permeability （μ′） and the magnetic loss tangent （tan δ） decrease. The substitution of Nd^3＋ for Fe^3＋ forms a secondary phase on the grain boundary of the matrix, which strongly restrains the grain growth of the matrix.

Effect of milling atmosphere on structural and magnetic properties of Ni-Zn ferrite nanocrystalline

Powder mixtures of Zn, NiO, and Fe2O3 are mechanically alloyed by high energy ball milling to produce Ni-Zn ferrite with a nominal composition of Ni0.36Zn0.64Fe2O4. The effects of milling atmospheres （argon, air, and oxygen）, milling time （from 0 to 30 h） and heat treatment are studied. The products are characterized using x-ray diffractometry, field emission scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and transmitted electron microscopy. The results indicate that the desired ferrite is not produced during the milling in the samples milled under either air or oxygen atmospheres. In those samples milled under argon, however, Zn/NiO/Fe2O3 reacts with a solid-state diffusion mode to produce Ni-Zn ferrite nanocrystalline in a size of 8 nm after 30-h-milling. The average crystallite sizes decrease to 9 nm and 10 nm in 30-h-milling samples under air and oxygen atmospheres, respectively. Annealing the 30-h-milling samples at 600℃ for 2 h leads to the formation of a single phase of Ni-Zn ferrite, an increase of crystallite size, and a reduction of internal lattice strain. Finally, the effects of the milling atmosphere and heating temperature on the magnetic properties of the 30-h-milling samples are investigated.

Impedance and Magnetization Studies of Ultrafine Ni-Zn Ferrite

Ultrafine Ni0.5Zn0.5 Fe2O4 powder was prepared by PVA aided chemical method. The powder and sintered pellets were characterised by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA) and complex impedance (Cl) analysis. The particles are found to be in the size range of 15 to 26 nm for various annealing temperatures. The coercivity, saturation magnetisation, Neel temperature and electrical conductivity are found to vary with sintering time at 800℃ for the pellet samples. The variations in the above intrinsic properties are explained qualitatively

Synthesis of Ni-Zn ferrite and its microstructure and magnetic properties

Nanometer Ni0.5Zn0.5Fe2O4 powders with spinel phase were prepared by the hydrothermal method using purified FeSO4 solution from sodium jarosite＇s slag as materials. The results show that the spinel phase of Ni0.5Zn0.5Fe2O4 powders begins to form at a relatively low temperature （130 ℃） and a shorter holding time （1 h） when pH=8. The crystallization kinetics equation at 200℃ is ln[-ln（1-x）] =-0.78＋0.951n t. The growth activation energy of Ni0.5Zn0.5Fe2O4 grains is 41.6 kJ/moL in hydrothermal synthesis process. With the increase of sintering temperature, the density and diameter shrinkage of ferrite circulus increase, whereas its pores decrease. The results of magnetic measurements show that saturation magnetic flux density Bs increases and the coercivity Hc decreases with the increase of their sintering temperature. Magnetic parameters of all the investigated samples satisfy the character demand of high Bs, low Br and low Hc of soft magnetic ferrite materials.

Effect of Cu ion substitution on structural and dielectric properties of Ni-Zn ferrites

A series of Cu-substituted Ni_(0.5-x)Cu_xZn_(0.5)Fe_2O_4(x=0.12,0.16,0.20,0.24 and 0.28) spinel ferrites were prepared by conventional ceramic method to investigate the effects of Cu compositional variation on the structure and dielectric properties.XRD patterns demonstrate that all the samples are crystallized in single-phase cubic spinel structure and the lattice constant increases with increasing Cu content.White grains observed by SEM are Cu-rich phase.The dielectric constant versus frequency curve displays a normal dielectric behavior of spinel ferrites.While the frequency dependence of dielectric loss tangent is found to be abnormal,exhibiting a peak at certain frequency for all Cu-substituted Ni-Zn ferrites.A maximum of the resistivity is observed at x=0.2 due to the decrease of hopping electrons between Fe^(2+) and Fe^(3+) in per unit volume,which is in contrast with the Cu content dependence of dielectric constant and dielectric loss.

Structural,magnetic,and dielectric properties of Ni-Zn ferrite and Bi_(2)O_(3)nanocomposites prepared by the sol-gel method

Ni-Zn ferrite and Bi_(2)O_(3)composites were developed by the sol-gel method.The structural,magnetic,and dielectric properties were studied for all the prepared samples.X-ray diffraction(XRD)was performed to study the crystal structure.The results of field emission scanning electron microscopy(FE-SEM)showed that the addition of Bi_(2)O_(3)can increase the grain size of the Ni-Zn ferrite.Magnetic properties were analyzed by a hysteresis loop test and it was found that the saturation magnetization and coercivity decreased with the increase of Bi_(2)O_(3)ratio.In addition,the dielectric properties of the Ni-Zn ferrite were also improved with the addition of Bi_(2)O_(3).

Effect of Cation Proportion on the Structural and Magnetic Properties of Ni-Zn Ferrites Nano-Size Particles Prepared By Co-Precipitation Technique

Ferrites having general formula Ni1-xZnxFe2O4 with x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were prepared by wet chemical co-precipitation method. The structural and magnetic properties were studied by means of X-ray diffraction, magnetization, and AC susceptibility measurements. The X-ray analysis confirmed the single-phase formation of the samples. The lattice parameter obtained from XRD data was found to increase with Zn content x. The cation distribution was studied by X-ray intensity ratio calculations. Magnetization results exhibit collinear ferrimagnetic structure for x≤0.4, and which changes to non-collinear for x〉0.4. Curie temperature TC obtained from AC susceptibility data decreases with increasing x.

Magnetic Properties of Ni-Zn Ferrites by Citrate Gel Method

Ni-Zn ferrite with a nominal composition of Ni1-xZnxFe2O4 (x = 0, 0.2, 0.6, 0.8, 0.9) are prepared by citrate gel method and characterized by X-ray diffraction. Magnetic properties of all samples are obtained by using VSM (Vibrating Sample Magnetometer) in the range of 10 Koe. The saturation magnetization values of the samples are carried out from the B-H loop. The effect of composition on saturation magnetization and magnetic moment are studied in this paper. The results showed that Saturation magnetization and magnetic moment values increases gradually as Zn2+ composition increases, it reaches maximum value 70.28 emu/gm for (x = 0.6) and decreases further with increasing Zn2+ composition.

Synthesis and Characterization of Ni-Zn Ferrite Nanoparticles (Ni_0.25Zn_0.75Fe₂O₄) by Thermal Treatment Method

Cubic structured nickel-zinc ferrite nanoparticles (Ni0.25Zn0.75Fe2O4) have been synthesized by thermal treatment method. In this procedure, an aqueous solution containing metal nitrates as precursors, polyvinyl pyrrolidone as a capping agent, and deionized water as a solvent were thoroughly stirred, dried at 353 K for 24 h, and crushed into powder before calcination to remove organic matters and crystallize the particles. The structure and particle size were characterized by X-ray powder diffraction and transmission electron microscopy. The average particle size increased from 7 to 25 nm with increase of calcination temperature from 723 to 873 K respectively. The magnetic properties were determined by vibrating sample magnetometer and electron paramagnetic resonance electron paramagnetic resonance at room temperature. By increasing the calcinations temperatures from 723 to 873 K it showed an increase of the magnetization saturation from 11 to 26 emu/g and the g-factor from 2.0670 to 2.1220. The Fourier transform infrared spectroscopy was used to confirm the presence of metal oxide bands at all temperatures and the removal of organic matters at 873 K.

Dielectric Properties of Ni-Zn Ferrites Synthesized by Citrate Gel Method

Ni-Zn ferrite with composition of Ni1-xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 0.9, 1.0) were prepared by citrate gel method. The Dielectric Properties for all the samples were investigated at room temperature as a function of frequency. The dielectric constant shows dispersion in the lower frequency region and remains almost constant at higher frequencies. The frequency dependence of dielectric loss tangent (tan δ) is found to be abnormal, giving a peak at certain frequency for mixed Ni-Zn ferrites. A qualitative explanation is given for the composition and frequency dependence of the dielectric loss tangent.

Effect of Aluminium Doping on Structural and Magnetic Properties of Ni-Zn Ferrite Nanoparticles

Aluminium doped Ni-Zn ferrite nanoparticles of general formula of Ni0.5Zn0.5AlxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0) have been synthesized by sol-gel auto combustion method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dis-persive X-ray (EDX), Fourier transform spectroscopy (FTIR) and vibrating sample magneto meter (VSM). XRD studies confirm that all compositions show single phase cubic spinel structure. The crystallite size was calculated using the Debye-Scherrer formula and found in the range of 17 - 52 nm. The lattice parameter “a” is found to decrease with increasing Al3+ content. The SEM images clearly show the crystalline structure and EDX patterns confirm the compositional formation of the synthesized compositions. The results of FTIR analysis indicated that the functional groups of Ni-Zn spinel ferrite were formed during the sol-gel synthesis process. The IR spectra showed two main absorption bands, the high frequency band ν1 around 600 cm-1 and the low frequency band ν2 around 400 cm-1 arising from tetrahedral (A) and octahedral (B) interstitial sites in the spinel lattice. As doping is increased the magnetic behavior is found to decrease and the composition x = 2.0 ferrite appears to be exhibiting superparamagnetism as the coercive field and retentivity are found near zero.

Microstructure and Microwave Absorption Properties of Y-Substituted Ni-Zn Ferrites

The Yttrium ions substituted Ni-Zn ferrites powders were prepared using a sol-gel technique. The crystal structure, magnetic properties and microwave absorption properties of the Ni-Zn ferrites powders were studied by X-ray diffraction, vibrating sample magnetometer and vector network analyzer. The results show that the microwave absorption properties of the Ni-Zn ferrites can be improved effectively with the substitution of Y ions. The minimum reflection loss of the Yttrium ions substituted Ni-Zn powder reaches –34.8 dB, with the –20 dB bandwidth over 2 GHz. The Yttrium substitution can improve microwave absorption properties of Ni-Zn ferrite due to smaller grain dimension and the higher specific

Significantly improved near-field communication antennas based on novel Ho^(3+)and Co^(2+)ions co-doped Ni-Zn ferrites

In near-field communication(NFC)antennas,soft magnetic ferrites are usually applied as a substrate to reduce eddy current loss and increase magnetic field coupling.For this purpose,the applied ferrites are required to have high permeability and saturation magnetization together with low magnetic loss and dielectric loss.However,for most soft magnetic ferrites,it is difficult to meet all the requirements.Herein novel Ni-Zn ferrite ceramics co-doped by Ho^(3+)and Co^(2+)ions with chemical formula Ni_(0.5-x)Zn_(0.5)Ho_(0.02)Co_(x)Fe_(1.98)O_(4)(x=0-0.2)were designed and prepared to balance these needs on the basis of molten salt synthesis with metal nitrates as raw materials and potassium hydroxide(KOH)as the precipitation agent and molten salt precursor.After the substitution of Ho^(3+),the saturation magnetization and initial permeability decrease,but with further doping of Co^(2+),the saturation magnetization gradually increases,while the initial permeability continues to decrease.When x=0.1,the sample will have the lowest dielectric constant,magnetic and dielectric loss,as well as the highest Curie temperature(305℃).Moreover,the acquired Ni-Zn ferrites have been applied simulatively in NFC antennas,revealing that the device manufactured with the optimal Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would have significantly improved performance at 13.56 MHz with low leakage and long transmit distance of magnetic field.Therefore,the Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would be a good candidate for NFC antenna substrates.

Research progress of permanent ferrite magnet materials

Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials.This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years.The emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and discussed.Specifically,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency.

Photocatalytic application of magnesium spinel ferrite in wastewater remediation:A review

This review paper explores the efficacy of magnesium ferrite-based catalysts in photocatalytic degradation of organic contaminates(antibiotic and dyes).We report the influence of different doping strategies,synthesis methods,and composite materials on the degradation efficiency of these pollutants.Our analysis reveals the versatile and promising nature of magnesium ferrite-based catalysts,offering the valuable insights into their practical application for restoring the environment.Due to the smaller band gap and magnetic nature of magnesium ferrite,it holds the benefit of utilising the broader spectrum of light while also being recoverable.The in-depth analysis of magnesium ferrites'photocatalytic mechanism could lead to the development of cheap and reliable photocatalyst for the wastewater treatment.This concise review offers a thorough summary of the key advancements in this field,highlighting the pivotal role of the magnesium ferrite based photocatalysts in addressing the pressing global issue of organic pollutants in wastewater.

Effective Elimination of Hazardous Chromium (VI) Using Periodic Elements and Contemporary Adsorption Methods by Using Magnesium Ferrite Nanoparticle: A Review

A well-known hazardous metal and top contaminant in wastewater is hexavalent chromium. The two forms of most commonly found chromium are chromate ( CrO 4 2− ) and dichromate ( Cr 2 O 7 2− ). Leather tanning, cooling tower blow-down, plating, electroplating, rinse water sources, anodizing baths etc. are the main sources of Cr (VI) contamination. The Cr (VI) is not only non-biodegradable in the environment but also carcinogenic to living population. It is still difficult to treat Cr contaminated waste water effectively, safely, eco-friendly, and economically. As a result, many techniques have been used to treat Cr (VI)-polluted wastewater, including adsorption, chemical precipitation, coagulation, ion-exchange, and filtration. Among these practices, the most practical method is adsorption for the removal of Cr (VI) from aqueous solutions, which has gained widespread acceptance due to the ease of use and affordability of the equipment and adsorbent. It has been revealed that Fe-based adsorbents’ oxides and hydroxides have high adsorptive potential to lower Cr (VI) content below the advised threshold. Fe-based adsorbents were also discovered to be relatively cheap and toxic-free in Cr (VI) treatment. Fe-based adsorbents are commonly utilized in industry. It has been discovered that nanoparticles of Fe-, Ti-, and Cu-based adsorbents have a better capacity to remove Cr (VI). Cr (VI) was effectively removed from contaminated water using mixed element-based adsorbents (Fe-Mn, Fe-Ti, Fe-Cu, Fe-Zr, Fe-Cu-Y, Fe-Mg, etc.). Initial findings suggest that Cr (VI) removal from wastewater may be accomplished by using magnesium ferrite nanomaterials as an efficient adsorbent.

Enhancing layered perovskite ferrites with ultra-high-density nanoparticles via cobalt doping for ceramic fuel cell anode

Nanoparticles anchored on the perovskite surface have gained considerable attention for their wide-ranging applications in heterogeneous catalysis and energy conversion due to their robust and integrated structural configuration.Herein,we employ controlled Co doping to effectively enhance the nanoparticle exsolution process in layered perovskite ferrites materials.CoFe alloy nanoparticles with ultra-high-density are exsolved on the(PrBa)_(0.95)(Fe_(0.8)Co_(0.1)Nb_(0.1))2O_(5+δ)(PBFCN_(0.1))surface under reducing atmosphere,providing significant amounts of reaction sites and good durability for hydrocarbon catalysis.Under a reducing atmosphere,cobalt facilitates the reduction of iron cations within PBFCN_(0.1),leading to the formation of CoFe alloy nanoparticles.This formation is accompanied by a cation exchange process,wherein,with the increase in temperature,partial cobalt ions are substituted by iron.Meanwhile,Co doping significantly enhance the electrical conductivity due to the stronger covalency of the Cosingle bondO bond compared with Fesingle bondO bond.A single cell with the configuration of PBFCN_(0.1)-Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)|SDC|Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ)(BSCF)-SDC achieves an extremely low polarization resistance of 0.0163Ωcm^(2)and a high peak power density of 740 mW cm^(−2)at 800℃.The cell also shows stable operation for 120 h in H_(2)with a constant current density of 285 mA cm^(−2).Furthermore,employing wet C_(2)H_(6)as fuel,the cell demonstrates remarkable performance,achieving peak power densities of 455 mW cm^(−2)at 800℃and 320 mW cm^(−2)at 750℃,marking improvements of 36%and 70%over the cell with(PrBa)_(0.95)(Fe_(0.9)Nb_(0.1))_(2)O_(5+δ)(PBFN)-SDC at these respective temperatures.This discovery emphasizes how temperature influences alloy nanoparticles exsolution within doped layered perovskite ferrites materials,paving the way for the development of high-performance ceramic fuel cell anodes.

A Design of Modular Interior Ferrite Magnet Fluxswitching Linear Motor for Track Transport

A novel topology of modular ferrite magnet fluxswitching linear motor(FMFSLM)use for track transport is presented in this paper,which enables more ferrite magnets to be inserted into the primary iron core.The motor has a significant low-cost advantage in long-distance linear drive.The proposed FMFSLM’s structure and working principle were introduced.Further,the thrust force expression of the motor was established.The thrust force components triggering thrust force ripple were investigated,and their expressions can be obtained according to the inductances’Fourier series expressions.Resultantly,the relationship between the harmonics of thrust force and that of self-and mutual inductances was revealed clearly.Based on the relationship,a skewed secondary should be practical to reduce the thrust force ripple.Thus,the effect of employing a skewed secondary to the proposed FMFSLM was investigated,and an optimized skewing span distance was determined.Finite element analysis(FEA)was conducted to validate the exactness of the theoretical analysis.The simulation results indicate that the strategy of suppressing thrust force ripple has a significant effect.Meanwhile,the motor maintains a good efficiency characteristic.The results of the prototype experiment are in good agreement with FEAs,which further verifies the proposed modular interior FMFSLM’s practicability.

Research on Heredity of Coarse Ferrite Grains

The changes in austenite grain size of the specimens with coarse ferrite grains under different heat treatment process were investigated.The focus was on studying the effect of annealing on refining coarse ferrite grains,as well as the influence of the ferrite grain size on the main technical indicators of gas carburizing.The results show that coarse ferrite grains may not necessarily cause the coarse austenite grains,but may result in mixed austenite grains.After annealing treatment,the coarse ferrite grains can be significantly refined and homogenized.Moreover,the coarse ferrite grains have no significant effects on hardnessand intergranular oxidationof gas carburizing.