Zn Ferrite Research Articles

Effect of V2O5 addition on the structural and magnetic properties of Ni–Co–Zn ferrites

The effect of V2O5 addition on the structural and magnetic properties of Ni–Co–Zn ferrites having the compositions Ni0.62Co0.03Zn0.35Fe2O4 + xV2O5 (where x = 0.0, 0.5, 1.0 and 1.5 wt%) are reported. The samples were prepared by solid state reaction. The crystalline structure of all the samples showed cubic spinel structure. The microstructural study reveals that the grain growths of Ni–Co–Zn mixed ferrites are strongly depended on the amount of V2O5 contents. The saturation magnetization and coercivity were determined from the magnetic hysteresis loops, while Curie temperatures were estimated from the temperature dependence of magnetization. The saturation magnetization almost linearly decreased from 77 emu g−1 for x = 0.0 wt% V2O5 to 56 emu g−1 for x = 1.5 wt% V2O5. Curie temperatures for the studied samples decreased with increase of V2O5 addition. A general termed of permeability enhancement is clearly evidenced on V2O5 addition.

Effect of sintering temperature on the structural, morphological, electrical, and magnetic properties of Ni–Cu–Zn and Ni–Cu–Zn–Sc ferrites

Polycrystalline Ni0.3Cu0.2Zn0.5Fe2O4 and Ni0.3Cu0.2Zn0.5Sc0.05Fe1.95O4 compounds have been prepared by standard solid-state reaction technique and sintered at 1000, 1100, 1150, 1200, and 1250 °C for 5 h in air. The effect of sintering temperature on the structural, morphological, magnetic, dielectric, and electrical properties of these spinel ferrites has been studied thoroughly and comparatively. Formation of the single-phase cubic spinel structure of these compositions is confirmed by X-ray diffraction analysis. The lattice constant increases with sintering temperature as well as with 5% scandium (Sc3+) doping in Ni–Cu–Zn ferrite. Surface morphology reveals that the grain size increases with sintering temperature. Among the prepared ferrites, Ni0.3Cu0.2Zn0.5Sc0.05Fe1.95O4 has the maximum density (5.05 × 103 kg/m3) at sintering temperature 1150 °C, which gives the highest value of initial permeability. It is observed that initial permeability varies with sintering temperature, and it gives the maximum value at optimum sintering temperature. It is noted that Curie temperature decreases with 5% Sc3+ ions doping, whereas it slightly increases with increasing sintering temperature for both compositions. Ni0.3Cu0.2Zn0.5Fe2O4 compound shows the highest Curie temperature 418 °C. Dielectric constant, dielectric loss factor and AC electrical conductivity decrease with 5% Sc3+ ions doping in Ni–Cu–Zn ferrite. The initial permeability decreases sharply at Curie temperature, which indicates a high degree of compositional homogeneity. The ‘Hopkinson’ peak is observed just below the Curie temperature in the real part of initial permeability versus temperature graphs. The mechanism of dielectric polarization and electrical conductivity has been explained based on the electron hopping between Fe3+ and Fe2+ ions. The variation trend of complex impedance and AC electrical conductivity reveals the semiconducting behavior of the ferrite samples. Formation of partial semicircles in the Z/-axis indicates that relaxation process is non-Debye type. The investigated ferrites show relatively high initial permeability, low magnetic loss, and low electrical conductivity in a wide frequency range, which make them potential candidate for various practical applications such as small and compact power suppliers for computers, microprocessors, microwave electronic devices, etc.

Градиентные структуры Ni – Zn ферритов для устройств защиты от электромагнитного излучения

Increasing the reliability requirements for electromagnetic compatibility of electronic equipment requires the creation of protective coatings that absorb electromagnetic radiation or the development of new radio-absorbing materials. In the frequency range up to 1 GHz, radio-absorbing materials based on Ni – Zn ferrites are of the greatest interest. The absorption of electromagnetic radiation by ferrites occurs due to resonant phenomena at the level of domains and atoms. Improving the performance of ferrites is possible by modifying their surface properties. In this paper, gradient structures for electromagnetic radiation protection products are obtained by treating the surface of Ni – Zn ferrite samples with a low-energy electron beam. To generate the electron beam, a unique development was used — a forevacuum plasma electronic source that allows forming and transporting a beam with a power density of up to 105 W/cm2 under conditions of high pressure and high gas release. As a result of processing, gradient structures were found on the surface of ferrites. A theoretical analysis and experimental study of the obtained structures “non – magnetic conductor – ferrite”, characterized by an increased attenuation coefficient and a reduced reflection coefficient of electromagnetic radiation in the frequency range from 0.5 to 2.5 GHz. The possibility of obtaining near-surface layers depleted in zinc with increased electrical conductivity and reduced magnetic permeability is shown.

Impact of Cr Substitution on Structural, Magnetic, Electric and Impedance Study of Mn-Ni-Zn Ferrites

A series of Cr3+-substituted Mn-Ni–Zn ferrites; Mn0.5Ni0.1Zn0.4Fe2-xCrxO4 (x = 0.0 - 0.4 in a step of 0.1) were prepared by traditional solid-state reaction route. The structural, magnetic, dielectric properties and impedance spectroscopy of these compositions were studied. Phase identification and lattice constant (a0) determination were carried out by X-ray diffraction (XRD). The XRD patterns established the fabrication of a single-phase spinel structure. The FESEM micrographs exposed that the average grain size () increased slightly with chromium (Cr) substitution and then decreased for a higher concentration of chromium in the composition. The real part of initial permeability () diminished owing to the enhanced porosity of the compositions with the increase of Cr3+ content in the composition. The highest relative quality factor (RQF) was attained for the samples with x = 0.1. The magnetic hysteresis was investigated to know the effect of Cr3+ substitution in the composition of the magnetic properties. The decrease of saturation magnetization (Ms) with an enhancement in Cr3+ might be triggered by switching of Fe3+ ions from octahedral to tetrahedral site. The samples with x = 0.1 exhibited the highest anisotropy constant (K). Curie temperatures of the investigated samples were significantly modified to lower temperatures with the Cr3+ content. The frequency characteristics of dielectric properties and impedance spectroscopy had been investigated. The highest dielectric constant (ε') and resistivity were observed for x = 0.1 and x = 0.2 samples. The complex impedance spectra analysis reveals in-depth information about the conduction mechanism, microstructure, and orientation of the grains in the samples.

Mechanical, optical and high-temperature magnetic properties of Sn-substituted Mg–Zn ferrites

ABSTRACT Sn-substituted Mg–Zn ferrites (0 ≤ x ≤ 0.10) have been synthesized using conventional ceramic technique and the mechanical, optical and high-temperature magnetic properties were studied. The formalism of elastic constants was assessed based on FTIR data. The mechanical stability was confirmed from the obtained values of stiffness constants. The bulk modulus, shear modulus and Young’s modulus have been estimated for different Sn concentrations. The Poisson’s ratio and Pugh ratio confirmed the brittleness character of the studied compounds. The Debye temperature was also calculated. The optical band gap has been calculated from diffuse reflectance spectra. The magnetization curves measured at different temperatures revealed the significant effect of temperature on the magnetic properties of the considered compositions. A second-order phase transition of ferrimagnetic to paramagnetic phase was observed in temperature-dependent magnetization vs. applied field and magnetic moment curves. The Curie temperature was observed to decrease owing to Sn substitution.

Investigation of dielectric behavior in Ni0.7-xZn0.3MxFe2O4 (M=Mn/Co/Cu) ferrites by impedance spectroscopy

The electrical characteristics of the Mn/Co/Cu-substituted Ni–Zn ferrites prepared using the citrate technique have been explored in detail by ac impedance spectroscopy. Measurements between temperatures (373K–523 K) were observed over a broad frequency range of 100 Hz–1 MHz. Maxwell and Wagner's model was used to analyze the frequency dependence of dielectric parameters. Dielectric loss tangent versus frequency plots show relaxation peaks due to the coincidence of the frequency of charge hopping between the localized state and the outer field. The Cole-Cole curve was designed to investigate the complex impedance of the current systems. Two semicircles corresponding to the grain and grain boundary were observed. The investigation of the electrical modulus includes the electrical relaxation of the non-Debye form. The substitution of Ni ions by Mn/Co/Cu ions indicates a major improvement in the dielectric characteristics of Ni − Zn ferrite. The Ni–Zn–Cu ferrite series displays the best dielectric properties suggesting the capability of this series to be suitable for high-frequency devices.

Extended properties of magnetic spins of zinc ferrite nanoparticles in the THz frequency range

We fabricated nanoparticles of Zn ferrite of the chemical formula ZnFe2O4 using the auto-combustion technique, and investigated their magnetic spin distribution and frequency response to optical excitation. Optical absorption and magnetic characterization of the nanoparticles were carried out in the UV–Vis and IR range, and extended on the low frequency side down to the THz domain. The nanoparticles were also characterized by X-ray diffraction and by magnetic force microscopy. The optical dielectric constant was calculated in both the UV–Vis and the THz domain. The optical bandgap, the dispersion energy and the oscillator strength of the nanoparticles were calculated from the optical data based on the single oscillator model. We measured the optical absorption, transmission and reflection spectra in the wavelength range from 200 to 800 nm, and calculated the refractive index, absorption and extinction coefficient. The optical band gap was found to be 1.14 eV and the oscillating energy of the dipole was determined to be 6.94 eV. The study shows that the coordination number of a metal complex and the symmetrical arrangement play an important role in determining the nanoparticle properties.

Interrelation between cationic distribution and electromagnetic properties of vanadium-substituted Mn–Zn ferrites

This study manifests the outcomes of varying vanadium (V) concentration in Mn–Zn ferrites with the general composition Mn0.6Zn0.4VxFe2−xO4 (x = 0.00—0.10, in steps of 0.02) synthesized by the solid-state reaction method. X-ray diffraction (XRD) analysis of all the samples confirmed the formation of the spinel structure. The cell parameter slightly decreases with the increase in V content. The substitution of V noticeably enhanced densification in samples sintered at 1250 °C. The grain size of the starting compositions varied from 13.0 to 27.9 µm. The Fourier Transform Infrared (FTIR) spectra indicate the preference of vanadium ions at octahedral sites. The saturation magnetization (Ms) and the experimental magnetic moments nB (µB) are observed to increase for x = 0.02 with = $${M}_{\mathrm{S}}$$ 61.73 emu/g. This happens for the reduction of the A–B interaction in the AB2O4 spinel type ferrites. After that, Ms and nB (µB) values decreased for higher V contents. The magnetization obtained is explained by redistribution of cations in the tetrahedral and octahedral sites and spin canting due to weakening of exchange interaction. The magnetic permeability and dielectric constant show a decreasing trend with increasing V concentration. The Cole–Cole plots demonstrate the grain and grain boundary effects. The manifestation of single semicircle after x = 0.06 indicates the precedence of grains in the overall resistance. The complex modulus graphs were also studied to understand the mechanism of the electrical processes.

The effect of Ce3+ doping on structural, optical, ferromagnetic resonance, and magnetic properties of ZnFe2O4 nanoparticles

Herein, we used the ultrasound irradiation to assist the sol–gel method for the synthesis of spinel ZnCexFe2 − xO4 nanoparticles. The patterns obtained from energy dispersive x-rays (EDX) analysis and elements mapping demonstrate the appropriate elemental stoichiometry and spatial distribution in the prepared samples. The Rietveld refinement patterns revealed the successful synthesis of the cubic-structured ZnFe2 − xCexO4 without any secondary phases. The crystallite size of ZnFe2 − xCexO4 ranged from 7 to 11 nm. Also, the optical bandgap for ZnFe2 − xCexO4 decreased from 2.1 eV to 1.77 eV. Electron paramagnetic resonance (EPR) spectroscopy was used to study the ferromagnetic resonance (FMR) characteristics of the ZnFe2 − xCexO4 samples. The resonance field was increased from 3362.65 Gauss to 3401.76 Gauss, while the line width decreased from 598.90 to 455.72 Gauss. The saturation magnetization was enhanced from 2.43 emu/g for x = 0.00 to 9.38 emu/g for x = 0.02. In addition, the values of coercivity (Hc) and remanence magnetization (Mr) were significantly lowered. The great value of saturation magnetization together with low values of Hc and Mr of Ce3+-substituted Zn ferrites makes them potential candidates for the microwave absorption field.

Regulation mechanism of metal ions towards magnetic properties in Mn1−xZnxFe2O4

In this work, the microstructure, crystallographic parameters and magnetic properties of polycrystalline manganese–zinc (Mn–Zn) ferrites were investigated. Mn1−xZnxFe2O4 (0.11 ≤ x ≤ 0.14) were prepared by the solid-state reaction method at 1360 °C for 2 h in air atmosphere. Phase evolution and microstructure of Mn–Zn ferrites were investigated by XRD and SEM techniques. X-ray diffraction study confirmed the formation of spinel-structured Mn1−xZnxFe2O4. The magnetic properties were measured employing soft magnetic alternating current measuring instrument (MATS-3010SA). It was observed that as the zinc content (x) increases, the lattice constant remained stable, microstructure did not change significantly, the permeability of Mn–Zn ferrite was improved, and total loss and coercivity were reduced. Changes in crystal structure and magnetism were attributed to occupancy of non-magnetic Zn2+ and super-exchange interactions between the metal ions of sub-lattice A and B in the spinel structure. These results indicated that the magnetic properties of Mn1−xZnxFe2O4 ferrites were strongly affected by the Zn content (x). In a brief summary, Mn0.86Zn0.14Fe2O4 ferrite exhibited excellent magnetic properties with a low loss (Ps = 39.24 W/kg) and low coercivity (Hc = 39.16 A/m) measured at 200 mT and 10 kHz.

Enhancement of structure, dielectric and magnetic properties of nanocrystalline Mn–Zn ferrites using Ni–Ti ions

The present work concerned with the effect of substitution of Fe3+ magnetic ion by magnetic and nonmagnetic ions together, Ni2+–Ti4+ ions. Ferrite samples with general formula Mn0.9Zn0.1NiyTiyFe2-2yO4 (0.0 < y ≤ 0.25) were prepared using conventional ceramic technique. Single phase cubic spinel structure of the studied samples was confirmed using X-ray diffraction pattern. The surface morphology and compositional features of the prepared samples were studied using scanning electron microscope (SEM) and EDAX measurements. The porosity and lattice parameter of the samples are calculated as a function of Ni–Ti concentration. Temperature, frequency and compositional dependence of the dielectric constant (e`), ac resistivity (ρ) and dielectric loss tangent (tan δ) were studied. All the samples give the normal dielectric behavior of ferrites with temperature and frequency. The experimental results indicate that e`, tan δ and ρ decrease as the frequency increase. This behavior was discussed on the basis of Maxwell–Wagner model and Koops theory. The imaginary part of dielectric modulus (M``) was calculated and plotted as a function of temperature. The hysteresis loop parameters were measured as a function of Ni–Ti content using VSM. The obtained results revealed that the dielectric properties of Mn–Zn ferrites enhanced by increasing Ni–Ti concentration where the ac resistivity increased 7 times and the dielectrics loss tangent reduced by 95% of un-substituted Mn–Zn ferrite. The present work indicates also that the sample Mn0.9Zn0.1Ni0.1Ti0.1Fe1.8O4 shows high ac resistivity, low dielectric loss and high magnetization and most suitable for microwave applications

Influence of bismuth doping on structural, electrical and dielectric properties of Ni–Zn nanoferrites

Bismuth doped Ni–Zn ferrites of the composition Ni0.5Zn0.5BixFe2-xO4 with (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.1) have been synthesized by a citrate precursor method. Bismuth was doped to tailor the properties of Ni–Zn spinel ferrite. X-Ray Diffraction (XRD) data was used to calculate lattice parameter, density, porosity and hopping length values which revealed that all annealed bismuth doped nickel zinc nanoferrites display a single phase cubic spinel structures. Average crystallite size was found to be in the range of 15–28 nm. Williamson-Hall method was used to deduce the average lattice strain experienced by the nanocrystalline. A tensile strain was observed with an increase in the bismuth concentration from x = 0.00 to x = 0.04 which leads to an expansion of lattice while a compressive lattice strain was observed for the concentration x = 0.06 due to contraction of the lattice. Fourier Transform Infra Red (FTIR) peaks confirmed the appearance of absorption bands at a wave number 405 cm−1 and at a wave number 580 cm−1 confirming tetrahedral and octahedral modes of vibrations respectively. I–V characteristics at 4 V voltage were studied at room temperature. A highly resistive behaviour of the samples of the order of 1010 Ω-cm was observed making these materials suitable for high frequency applications. The investigations on real part, imaginary part of dielectric constant and dielectric loss tangent were carried out in the frequency range 10 kHz to 10 MHz at room temperature. Dielectric behaviour showed that with an increase in concentration of bismuth, the value of real part of dielectric constant increases from 5.161 to 11.162 at 104 Hz frequency and the value of dielectric loss tangent decreases from 0.79 to 0.33. AC conductivity of all the samples was found to increase with an increase in frequency which is explained on the basis of Koop's Phenomenological theory.

Ni0.4Zn0.6Fe2O4 Nanopowders by Solution-Combustion Synthesis: Influence of Red/Ox Ratio on their Morphology, Structure, and Magnetic Properties

Nickel-zinc ferrite nanopowders Ni0.4Zn0.6Fe2O4 were prepared by glycine (G)–nitrate (N) solution-combustion synthesis and the influence of G/N ratio on their chemical composition, morphology, structure, crystallite size, and magnetic behavior was characterized by XRD, EDX, SEM, FTIR spectroscopy, and vibration magnetometry. According to XRD data, the formation of Ni–Zn ferrite gets started at G/N = 0.4. The observed influence of G/N ratio on the structural and magnetic parameters of Ni–Zn ferrites opens up a route to producing powders with crystallite size D in the range 24.6–47.1 nm, extent of conversion α up to 94%, coercive force Hc from 7.88 to71.78 Oe, remanence magnetization Mr from 2.42 to 31.81 emu/g, and saturation magnetization Ms from 51.06 to 90.66 emu/g. The maximum values of magnetic characteristics were reached at a stoichiometric ratio of glycine to nitrogen in nitrates (G/N = 0.6).

Influences of La3+ ion substitution on dielectric, susceptibility and permeability properties of Mg–Zn ferrite nanoparticles

Nanoparticles of lanthanum-substituted magnesium zinc ferrites with general formula Mg0.6Zn0.4La2yFe2−2yO4 (where y = 0.0, 0.05, 0.1, 0.15, 0.20 and 0.25) were prepared by employing co-precipitation (wet chemical) method. Phase formation was evaluated by X-ray diffraction analysis. Scanning electron microscopic analysis revealed interlocked nanoparticles exhibiting grain size varies between 300 and 95 nm. Initial permeability (µi) and Curie temperature (TC) decrease with lanthanum content. The synthesized lanthanum-substituted Mg–Zn ferrite nanoparticles displayed single-domain ferromagnetic behaviour below Curie temperature TC and superparamagnetic cluster above TC. The effects of lanthanum substitution on structural, electrical and magnetic properties of Mg–Zn ferrites were studied. The present investigation revealed that lanthanum substitution and content have great influence on the structural, electrical and magnetic properties of Mg–Zn ferrites.

Magnetic, microstructural and photoactivated antibacterial features of nanostructured Co–Zn ferrites of different chemical and phase compositions

Ferrites have found extensive uses in electrical, chemical and mechanical engineering, but their potential as biomaterials remains largely unexplored. Here we report on the use of a flash method based on urea decomposition to synthesize four different compositions of cobalt and zinc ferrite, including monophasic CoFe2O4, ZnFe2O4 and Co0.5Zn0.5Fe2O4, and CoFe2O4/ZnFe2O4 nanocomposite. Zn-ferrite nanoparticles were approximately the same size as those of Co-ferrite, but were better dispersed, rougher, more crystalline and less pronouncedly faceted. The mixed, monophasic Co0.5Zn0.5Fe2O4 composition was morphologically most similar to single-phase Co-ferrite. In the biphasic mixture of CoFe2O4 and ZnFe2O4, smooth and polydisperse Co-ferrite grains were coated by finer, cuboid and monodisperse Zn-ferrite nanoparticles. The porosity and the roughness of this composition were the highest, and so was its coercivity owing to the shielding of the ferrimagnetic Co-ferrite grains by the paramagnetic Zn-ferrite nanoparticles. Expectedly, the highest saturation magnetization (66.3 emu/g) was detected in Co-ferrite and the lowest (2.8 emu/g) in Zn-ferrite. Co-ferrite also exhibited the highest magneto-crystalline anisotropy, remanence and hysteresis loop area, while the highest exchange bias and susceptibility were found in the mixed, Co0.5Zn0.5Fe2O4 composition. All four ferrite compositions were biocompatible with human fibroblasts, but they demonstrated different antibacterial activities against Gram-negative E. coli and Gram-positive S. aureus, with the biphasic mixture of CoFe2O4 and ZnFe2O4 being more effective than Co0.5Zn0.5Fe2O4, CoFe2O4 or ZnFe2O4. Further, all the compositions were more active against both bacterial species under visible light than in the dark, indicating the photocatalytic formation of electron-hole pairs and reactive oxygen species that exert a damaging effect on the bacterial cells as the prime mechanism of action.

Zinc substitution effect on the structural, spectroscopic and electrical properties of nanocrystalline MnFe2O4 spinel ferrite

This paper reports the structural, morphological, spectroscopic, dielectric, ac conductivity, and impedance properties of nanocrystalline Mn1-xZnxFe2O4. The nanocrystalline Mn–Zn ferrites were synthesized using a solvent-free combustion reaction method. The structural analysis using X-ray diffraction (XRD) pattern reveals the single-phase of all the samples and the Rietveld refined XRD patterns confirmed the cubic-spinel structure. The calculated crystallite size values increase from 8.5 nm to 19.6 nm with the Zn concentration. The surface morphological analysis using field emission scanning electron microscopy and the transmission electron microscopy confirms the nano size of the prepared ferrites. X-ray photoelectron spectroscopy was used to study the ionic state of the atoms present in the samples. Further, the high-resolution Mn 2p, Zn 2p, Fe 2p, and O 1s spectra of Mn1-xZnxFe2O4 does not result in the appearance of new peaks with Zn content, indicating that the Zn substitution does not change the ionic state of Mn, Zn, Fe, and O present in nanocrystalline Mn1-xZnxFe2O4. The investigated electrical properties show that the dielectric constant, tan δ and ac conductivity gradually decrease with increasing Zn substitution and the sample Mn0·2Zn0·8Fe2O4 has the lowest value of conductivity at 303 K. The ac conductivity measured at different temperatures shows the semiconducting nature of the ferrites. The impedance spectra analysis shows that the contribution of grain boundary is higher compared with the grain to the resistance. The obtained results suggest that the Zn substituted manganese ferrite nanoparticles can act as a promising candidate for high-frequency electronic devices applications.

State-of-the-art for Magnetorheological Elastomers Fabrication and Hydro-tribological Characterisation

Magnetorheological effect on mechanical properties of its specific applications has been studied. Mechanical properties such as hardness, tribology characteristic and salt water and water absorption with hygrothermal effect will be further studied on wear performance of MRE on marine equipment applications. Isotropic, anisotropic and anisotropic with added N330 carbon black filler of Ni Zn Ferrite Magnetorheological Elastomers (MREs) were prepared with Ni Zn Ferrite filler, Ni1 - xZnxFe2O4 particles weight fraction of 70%. Images of Scanning Microscopy Electron (SEM) and Energy Dispersive X-Ray Analysis (EDX) are identified with the presence of the structure of Ni Zn Ferrite in the natural rubber matrix. Anisotropic Ni Zn Ferrite MREs with added carbon black filler given highest hardness value of 90.78; least effected on salt water and water absorption and hygrothermal effect; better wear performance with a low average specific coefficient of friction(COF), specific wear rate and least loss of wear volume. Therefore, it is most suitable use for future application in a wet environment for a long period.

Structural, Magnetic and DC Electrical Resistivity Studies of Ni–Zn–Cr Ferrites Prepared by the Citrate-Gel Auto-Combustion Method

Nanocrystalline chromium substituted Ni–Zn nanoferrites with composition Ni0.5Zn0.5CrxFe2−xO4 (0 ≤ x ≤ 0.25, in steps of 0.05) have been synthesized using citrate-gel auto-combustion method. The as synthesized powder of the starting composition has been characterized by using TG–DTA in air atmosphere for the temperature up to 800 °C and X-ray diffraction for its structure. Upon confirming the spinel phase for the starting composition, the chromium substituted Ni–Zn ferrite nano powders were synthesized by the similar procedure. The as synthesized powders were pressed into pellets and toroids under uniaxial pressure followed with sintering in air atmosphere for 4 h at 1100 °C for electrical and magnetic characterizations. The X-ray diffraction studies revealed a decrease of the lattice constant and considerable modification in the structure of Ni–Zn ferrite with the substitution of Cr3+ for Fe3+ ions. The room temperature FT-IR spectra displayed three significant IR absorption bands in the wave number range of 350–600 cm−1 which is a characteristic of the spinel structure. The band positions and intensities were found to vary with chromium substitution in Ni–Zn ferrite. The room temperature DC electrical resistivity and activation energy for conduction in the Ni–Zn–Cr ferrite samples were measured by using the two-probe method while the AC resistivity studies were carried out in the frequency range of 1 kHz to 13 MHz and the all the observations have been discussed in the light of existing understanding.

Magnetic, electrical, and structural properties of Mg2+-doped nickel–zinc ferrite prepared by sol–gel–SHS method

Magnesium-substituted Ni–Zn ferrite (Ni0.5Zn0.5−xMgxFe2O4, x = 0–0.3, in steps of 0.05) has been successfully synthesized via a sol–gel–SHS (self-propagating high-temperature synthesis) method. The Fourier transform infrared spectra indicate the formation of spinel structure for Ni–Mg–Zn ferrites by sol–gel–SHS method. Thermogravimetric analysis reveals that the lowest decomposition temperature of SHS powder is approximately 400 °C. X-ray powder diffraction results signify a single-phase nature of cubic spinel structure for these samples without any detectable impurity phase. Lattice constant gradually decreases as the magnesium content continuously increases, while the average crystallite size increases except for undoped sample. Scanning electron microscopy images demonstrate that the samples consist of regular shaped grains without any phase segregation and agglomeration. Magnetization measurements indicate that all samples display a typical soft ferromagnetic characteristic with an abnormal saturation magnetization peak at x = 0.15. The frequency dependence of dielectric constant of the synthesized Ni–Mg–Zn ferrite exhibits a normal dielectric behavior, while the dielectric loss shows an abnormal peak behavior. The modulation mechanism for magnesium-substituted Ni–Zn ferrite on structure, electrical, and magnetic properties is systematically discussed.

Influence of Zn2+ doping towards the structural, magnetic, and dielectric properties of NiFe2O4 composite

The present work is aimed to study the changes in characteristics of nickel ferrites followed by the zinc doping and for that, the nanocrystalline Ni–Zn ferrites (Ni1−xZnxFe2O4: x = 0, x = 0.2 and x = 0.4) were prepared via sol–gel auto combustion method and by annealing at subsequent temperature. The physical characterization studies of the final composite provided that the lattice structure of Zn2+ substituted at Ni sites confirms for the single-phase ferrite with spinel structure got investigated at room temperature (RT) with functional, morphological as well as temperature-dependent magnetic and dielectric properties. The magnetic properties imply that the distribution of cations at the lattice sites suggests that the magnetization is getting increased with a decrease of temperature from RT to lower temperature in a field cooling process and is due to the strong dipolar magnetostatic interactions between the individual magnetic moments, which also affirms that the magnetization decreases with a decrease of Ni concentration. The coercively extracted from isothermal magnetization curves attributed to the single domain nature at RT. Further, the dielectric constant (e′) and dielectric loss (tan δ) are also examined and found to be strongly dependent on the function of frequency and temperature. The change in e′ and tan δ demonstrated that the dispersion due to the Maxwell–Wagner interfacial polarization and is in a good agreement with Koop’s theory.