Single Phase Spinel Structure Research Articles

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.

To study the surface modified cobalt zinc ferrite nanoparticles for application to magnetic hyperthermia

In the present work, we have studied the influence of the annealing temperature and concentration of Co0.5Zn0.5Fe2O4 nanoparticles as a heat generation material for hyperthermia therapy. Cobalt zinc ferrite (Co0.5Zn0.5Fe2O4) nanoparticles were synthesized by the chemical co-perception method and annealed at 200 °C, 400 °C, and 600 °C for 3 h. The structural characterization was carried out using an x-ray diffractometer, and all samples exhibit a single-phase spinel structure. The M-H loop of the as-dried and annealed samples revealed a narrow “S” shaped hysteresis cycle, which exhibits the superparamagnetic behavior of all samples. The Mössbauer spectrum of all samples at room temperature showed a doublet, which is the signature of the superparamagnetic nature, and it is in good agreement with the acquired M-H curves. Surface modifications of the as-dried and annealed nanoparticles were achieved by coating the nanoparticles with chitosan, and solutions of different concentrations (1 mg/ml, 2 mg/ml, 4 mg/ml, and 6 mg/ml) were prepared. Employing dynamic light scattering measurement, the hydrodynamic diameter of the chitosan-coated nanoparticles at 37 °C was found to be between 173 nm and 231 nm, and the polydispersity index was less than 0.30 for all concentrations. The induction heating measurements indicated that the heating efficiency of chitosan-coated nanoparticles increased according to the order of annealing temperature (600 °C > 400 °C > 200 °C> as-dried) and the solution of concentration (6 mg/ml > 4 mg/ml > 2 mg/ml > 1 mg/ml).

Effect of Ni Substitution on Optical Transitions and Magnetic Behavior of Mesoporous NixCo3−xO4 (0 ≤ x ≤ 1) Thin Films Prepared by Electrophoretic Deposition

High-quality nickel cobaltite (NixCo3−xO4, 0 ≤ x ≤ 1) nanopowders with various nickel contents have been prepared by a facile hydrothermal method, calcined in air at 300°C for 2 h, then coated on the surface of indium tin oxide sheets by electrophoretic deposition. The optical, microstructural, and magnetic properties were characterized by x-ray diffraction (XRD) analysis, ultraviolet–visible (UV–Vis) spectrophotometry, field emission-scanning electron microscopy (FE-SEM), and vibrating-sample magnetometry. The XRD patterns of the pure and Ni-doped Co3O4 powders revealed the formation of single-phase spinel structure, without any impurity phases for all samples. The position and intensity of various absorption bands in the UV–Vis spectra were influenced by the distribution of Co2+ and Ni2+ ions at tetrahedral sites of the spinel structure, revealing that O2− → Co2+ and O2− → Ni2+ transition sites were affected by increasing the Ni2+ content, thereby changing the optical properties of NixCo3−xO4. Vibrating-sample magnetometry analysis revealed that the magnetic nature of the prepared nanopowders changed from anti-ferromagnetic to very weak ferrimagnetic.

Synthesis of High Entropy Oxide through Sol-Gel Method

High entropy oxides composed of Ag, Al, Zn, Cr, and Cu are synthesized through sol-gel method. The metal nitrates, including silver nitrate, aluminum nitrate, zinc nitrate, chromium nitrate, and copper nitrate, are firstly dissolved in distilled water and stirred for one hour at room temperature. After mixing thoroughly, citric acid will be added into the solution as the coordinating agent to catch all metal atoms and stirred for another half an hour. Then, by adding ammonia, the pH value of the solution is adjusted to seven and the solution is dried in the oven at 90oC for 48 hours. After that, the powder was annealed at 300oC for one hour to obtain the final product. The x-ray diffraction pattern shows that AgAlZnCrCuO exhibited a single-phase spinel structure with the second phase of CuO. Interestingly, based on the scanning electron microscope image, the AgAlZnCrCuO nanoparticles show highly porous morphologies, suggesting that the AgAlZnCrCuO may possess the unique potential application for electrochemical process.

Tuning of physical properties of multifunctional Mg-Zn spinel ferrite nanocrystals: a comparative investigations manufactured via conventional ceramic versus green approach sol-gel combustion route

This work focused on the impact of synthesis routes on the structural, microstructural, magnetic, electrical and dielectric characteristics of Mg1−x Zn x Fe2O4 (x = 0.00, 0.25, 0.50, 0.75, and 1.00) nanocrystals manufactured via the ceramic and green approach sol–gel route. The powder X-ray diffraction (XRD) analysis reveals that the entire synthesized ferrite solids crystallize in single phase spinel structure. The XRD outcomes highlight the impact of the synthesis routes and Zn2+ replacement on the morphology, crystallite size and structural parameters of magnesium nano-ferrites. The transmission electron microscopy (TEM) images illustrate that the process of synthesis causes extensive lessening of grain and crystallite sizes. The magnetic study reveals that the magnetic properties of magnesium ferrite can be tuned by zinc substitution. The saturation magnetization (Ms), retentivity (Mr), coercive force (Hc) and magneton number diminutions meaningfully with the replacement of diamagnetic Zn2+ ions in Mg-ferrite for both the synthesized systems. The deterioration of magnetic parameters with Zn2+ substitution can be clarified on the base of the random spin canting model. Likewise, the magnetic parameters, enhanced meaningfully for sol-gel derived samples this can be attributed due to decline of crystallite size effect. The DC electric resistivity displays NTCR behaviour like ideal semiconducting materials for all the produced samples. The DC resistivity values of sol-gel produced samples were found to be little bit higher than that of ceramic derived samples. The experimental dielectric constant as a function of frequency behaviour can be elucidated with the support of the heterogeneous model of the polycrystalline structure of ferrites. The dielectric constant and loss tangent decreases with Zn2+ content for both the systems. The dielectric constant enhances for sol-gel derived samples; however, lower values of loss tangent were found. The obtained outcomes can be suitable for multifunctional applications in electronics devices and biomedical field.

Investigation of Structural, Optical, and Dielectric Properties of Co0.5Cd0.5-xCuxFe1.95Ce0.05O4 Nanoferrites

Co0.5Cd0.5-xCuxFe1.95Ce0.05O4 (0 ≤ x ≤ 0.5) nanoferrites were successfully synthesized via sol-gel-assisted autocombustion method. The effects of Cu substation in the spinel matrix on structural, optical, and dielectric properties have been studied. XRD data confirms the successful synthesis of single phase cubic spinel structure. FTIR spectroscopy and Raman spectroscopy further confirm the formation of single phase spinel structure. Ultraviolet-visible (UV-vis) spectroscopy is used to measure the energy bandgap of the prepared samples. The energy bandgap is found in the range 1.02 to 1.96 eV and decreases when Cu concentration increases. Dielectric parameters like dielectric constant, tangent loss, and ac impedance are determined as a function of frequency of applied field and are described with the help of Koop’s theory. It is observed that all these parameters decrease with increase in frequency and become independent of frequency above 1 MHz. The dielectric properties of Cu-substituted Co-Cd spinel ferrites make these ferrites potential candidate for applications in high frequency range.

The influence of the starch coating on the magnetic properties of nanosized cobalt ferrites obtained by different synthetic methods

To investigate the magnetic behavior of starch-coated cobalt ferrites, well-established synthetic methods, i.e., coprecipitation, mechanochemical, ultrasonically assisted coprecipitation, microemulsion, and microwave-assisted hydrothermal syntheses were chosen for their preparation. The obtained materials had pure single-phase spinel structures. Scanning and transmission electron microscopy analyses revealed that the morphology of the samples is not uniform, and particle aggregation is a dominant process. Fourier transform infrared spectra and thermogravimetric analysis confirmed the presence of starch in all–coated samples. The unusually higher saturation magnetization of starch-coated samples than their as-prepared analogs, obtained by coprecipitation, ultrasonically assisted coprecipitation, and microwave-assisted hydrothermal methods, might be explained by the Ostwald ripening mechanism induced by the coating process. A decrease in magnetization was noticed for the starch-functionalized nanomaterials synthesized by mechanochemical and microemulsion methods, in comparison to their as-prepared analogs, i.e., the size distribution of such nanoparticles is narrow, and the average diameter of the grains is near critical for the Ostwald ripening process.

An Accurate Low Temperature Cation Distribution of Nano Ni-Zn Ferrite Having a Very High Saturation Magnetization

Structural and magnetic properties of nanocrystalline Ni0.65Zn0.35Fe2O4 synthesized by sol-gel method have been analyzed using various characterization techniques. The single-phase spinel structure and crystallite size have been obtained from X-ray diffraction (XRD). The experimentally observed high specific saturation magnetization, 176 emu/g at 10 K, has been discussed in terms of core-shell contributions based on spin canting of nano Ni0.65Zn0.35Fe2O4 with the help of infield Mossbauer study at 5 K. The proposed cation distribution relied upon infield Mossbauer spectra and the Rietveld analysis of the neutron diffraction and XRD data and provides an insight to improve the properties of this material suitable for high-frequency applications.

Synthesis and Characterization of Cobalt Ferrite through Co-Precipitation Technique

The device formation in current technology demands effective magnetic materials. Cobalt ferrite nanoparticles were synthesized by the co–precipitations method using the precursor materials (Fe(No3)3 9H2O) and (Co(NO3)2 6H2O). X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) analysis, and UV–Visible absorption spectral studies were used to analyze the structural, chemical/functional groups with possible stretching and optical bandgap properties of the CoFe2O4 powder. XRD results designate that the resultant particles are crystalline, pure single-phase spinel structure. From the FTIR analysis reveals that C-C, C=O stretching, and the shift is leaked indicating that the presence CoFe2O4. The absorption and the optical band gaps values are increased trend with temperatures also evidence that is enhancing magnetic behavior.

Photocatalytic activity of cobalt substituted zinc ferrite for the degradation of methylene blue dye under visible light irradiation

Cobalt-zinc ferrite with composition CoxZn1-xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) was synthesized using citrate precursor method and the prepared samples were characterized by using X-ray powder diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) techniques. Single phase spinel structure was confirmed by the XRD patterns having (311) characteristic peak. SEM images showed the agglomeration of the powdered samples of cobalt-zinc ferrite. TEM images record an average crystallite size of 52 nm. Visible range light was used for the photocatalytic degradation of methylene blue by creating a Fenton-type system. It was observed that the degradation of methylene blue was enhanced with an increase in cobalt concentration. The degradation efficiency reached a maximum (77%) for x = 0.5 while it was the smallest (∼65%) for x = 0.0 in 1 h under visible light irradiation. Hence, we conclude that cobalt-zinc ferrite can be used as a potential material for purification of water and its degradation efficiency increased with an increase in cobalt concentration.

Synergy effects between Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and CuO-Bi2O3 mixtures in low-temperature sintered LiZnTi ferrites with enhanced gyromagnetic and microwave dielectric properties

Promoting grain growth and optimizing microstructure are valid strategies for enhancing gyromagnetic and microwave dielectric properties of low-temperature sintered ferrite materials. Here, a modified low-temperature sintering technique was attempted for the synthesis of LiZnTi ferrites that have compact microstructure and improved performances. Trace amounts of CuO-Bi2O3 mixtures (0.50 wt%) were adopted as sintering additives to promote grain growth and to reduce the sintering temperature. Meanwhile, Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles (∼21.9 nm) were synthesized using a sol-gel auto-combustion method and were used to optimize the microstructure and to restrain abnormal grain growth. XRD Rietveld refinement and SEM images revealed that uniform and dense LiZnTi ferrites with single-phase spinel structure were obtained. Results demonstrated that co-doping of Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and CuO-Bi2O3 mixtures allows low-temperature sintering (900 °C) to be achieved and also promotes grain growth and densification. In particular, LiZnTi ferrites that were modified with 5.00 wt% Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and 0.50 wt% CuO-Bi2O3 sintering additives exhibited narrow ferromagnetic resonance linewidth (ΔH, ∼145 Oe) and low dielectric loss tangent (tanδε, ∼2.45 × 10−4) at ∼9.50 GHz, high saturation flux density (Bs, ∼364 mT), and high squareness ratio (Br/Bs, ∼0.89). Such a modified sintering technique at a low sintering temperature, as reported in this work, provides a reference for other advanced ferrites.

Cation exchange in Ni–Cu–Zn aluminate spinels revealed by EXAFS

Nanocrystalline Ni–Cu–Zn aluminate powders (Ni1-xCuxAl2O4, Cu1-xZnxAl2O4, and Zn1-xNixAl2O4) with different divalent ion concentrations (0 ​≤ ​x ​≤ ​1) were successfully synthesized by the sol-gel auto combustion method using diethanolamine (DEA) as a novel fuel. The structural, morphological, and the local atomic structures of each calcined sample were investigated by XRD, TEM, and synchrotron EXAFS measurements. The XRD results confirmed the formation of single-phase spinel structure with Fd-3m space group of all samples. When XRD Rietveld refinement and Williamson-Hall analysis were applied to the XRD data, the exact crystallite size and structural parameters were obtained. The EXAFS spectra showed the main translocation trends in the trivalent (Al3+) and divalent (Ni2+, Cu2+, Zn2+) ions between the tetrahedral (A) and octahedral (B) sublattices. Furthermore, the degree of inversion in these spinel aluminates is completely dissimilar and identified as 0.493–0.499 for Ni1-xCuxAl2O4, 0.254–0.498 for Cu1-xZnxAl2O4 and 0.093–0.453 for Zn1-xNixAl2O4 series, as indicated by the multiple-edge curve-fitting analysis of Ni, Cu, and Zn K-edge EXAFS spectra. These values comprise essential data for comprehension of numerous relevant properties.

Study the magnetic and dielectric properties of Sn substituted nickel–cobalt ferrite synthesized by auto combustion method

Nickel–cobalt ferrites with the stoichiometry of Ni0.4Co0.6–xSnxFe2O4 (where, x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) have been synthesized by the auto combustion method. The X-ray diffraction (XRD) pattern discloses a single-phase spinel structure, and the crystallite sizes of the nanoparticles are estimated at about 12–28 nm. The diffraction peak shifts towards the lesser angle and the lattice parameter slightly improves with the Sn substitution. The surface morphology and elemental composition are examined by the scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX), respectively. At room temperature, the bulk density, grain size, and coercivity are increased with the Sn substitution. The hysteresis loops of this sintered specimen display an improved magnetic behavior at ambient temperature. The saturation magnetization increases initially and reaches to the maximum at x = 0.02 (78.05 emu/g) then decreases with higher Sn substitution. All the sintered species retain in the multi magnetic domain. Prepared samples demonstrate a slight reduction both in dielectric constant (e׳) and loss tangent (tanδ) with an increment of the Sn substitution. The proposed work is expected to open the possible emersion of the ferrite in the high-frequency applications.

A new eight-cation inverse high entropy spinel with large configurational entropy in both tetrahedral and octahedral sites: Synthesis and cation distribution by X-ray absorption spectroscopy

In this work we report the synthesis of (Co,Mg,Mn,Ni,Zn)(Al,Co,Cr,Fe,Mn)2O4 in a single-phase spinel structure (space group Fd3¯m). The chemical homogeneity and purity of the sample were checked through X-ray diffraction, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The analysis of the pre-edge peaks of the X-ray absorption spectra for all the transition metals clearly indicated the presence of a partial degree of inversion in the spinel structure. This material is characterized by a particularly large configurational entropy, regarding both the A and the B sites, leading to a total value equal to 3.3 in R unit.

Stabilizing Oxygen Vacancy in Entropy-Engineered CoFe2O4-Type Catalysts for Co-prosperity of Efficiency and Stability in an Oxygen Evolution Reaction.

We used entropy engineering to design a series of CoFe2O4-type spinels. Through microstructural characterization, electrochemical measurements, and X-ray photoelectron spectroscopy, we demonstrated that the entropy-stabilized oxide (Co0.2Mn0.2Ni0.2Fe0.2Zn0.2)Fe2O4 has a single-phase spinel structure and exhibits both efficient and stable catalytic oxygen evolution. This is attributable to disordered occupation of multivalent cations, which induces severe lattice distortion and increases configurational entropy, thereby facilitating formation of structurally stable, high-density oxygen vacancies on the exposed surface of the spinel. Thus, more catalytic sites on the surface are activated and retained over the course of long-duration testing for oxygen evolution. Entropy engineering expands researchers' access to catalysts that link entropy-stabilized structures to useful properties.

Incremental substitution of Ni with Mn in NiFe2O4 to largely enhance its supercapacitance properties

By using a facile hydrothermal method, we synthesized Ni1−xMnxFe2O4 nanoparticles as supercapacitor electrode materials and studied how the incremental substitution of Ni with Mn would affect their structural, electronic, and electrochemical properties. X-ray diffractometry confirmed the single-phase spinel structure of the nanoparticles. Raman spectroscopy showed the conversion of the inverse structure of NiFe2O4 to the almost normal structure of MnFe2O4. Field-emission scanning electron microscopy showed the spherical shape of the obtained nanoparticles with a size in the range of 20–30 nm. Optical bandgaps were found to decrease as the content of Mn increased. Electrochemical characterizations of the samples indicated the excellent performance and the desirable cycling stability of the prepared nanoparticles for supercapacitors. In particular, the specific capacitance of the prepared Ni1−xMnxFe2O4 nanoparticles was found to increase as the content of Mn increased, reaching the highest specific capacitance of 1,221 F/g for MnFe2O4 nanoparticles at the current density of 0.5 A/g with the corresponding power density of 473.96 W/kg and the energy density of 88.16 Wh/kg. We also demonstrated the real-world application of the prepared MnFe2O4 nanoparticles. We performed also a DFT study to verify the changes in the geometrical and electronic properties that could affect the electrochemical performance.

Effect of chromium substitution on structural, electrical and magnetic properties of NiZn ferrites

Ni0.5Zn0.5Fe2−xCrxO4 (0≤x≤0.5) ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural, electrical and magnetic properties. X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase. As chromium concentration increases, the lattice parameter and crystallite size gradually decrease. The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+ doping, changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5. While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+ substitution, reaching up to 1.1×108 Ω·cm at x=0.5. The dielectric constant monotonously decreases with rising frequency for these ferrites, showing a normal dielectric dispersion behavior. The compositional dependence of dielectric constant is inverse with that of electrical resistivity, which originates from the reduced Fe2+/Fe3+ electric dipole number by doping, indicating inherent correlation between polarization and conduction mechanism in ferrite.

Effects of MgO addition on the DC-bias-superposition characteristic of low-temperature-fired NiCuZn ferrites

Microstructure and magnetic properties, especially the DC-bias-superposition characteristic of the MgO-doped and low temperature fired NiCuZn ferrites, were investigated. X-ray diffraction (XRD) patterns showed a single-phase spinel structure for all samples. The microstructure manifested little change with MgO content. Initial permeability, sintered density and saturation magnetic flux density (Bs) monotonously decreased; however, coercive force (Hc) gradually increased with increasing MgO content. MgO addition mode could effectively consider both initial permeability and DC-bias-superposition characteristic of the NiCuZn ferrites. With 1.5 wt% to 2.5 wt% of MgO addition content, the ferrites could obtain high initial permeability of 70–85 with H70% of 846–700 A/m, indicating good application prospect in the field of chip power magnetic devices.

Influence of High-Temperature Annealing on Structural and Magnetic Properties of Crystalline Cobalt Ferrite Nanoparticles in the Single-Domain Regime

We have carried out a systematic study on the effect of high-temperature annealing on the structural and magnetic properties of ultra-small crystalline cobalt ferrite nanoparticles prepared by the hydrothermal method. The structural and the magnetic characterizations of nanoparticles were investigated by XRD, TEM, FTIR, and VSM. The results of Rietveld refinement revealed that the nanoparticles have a cubic single-phase spinel structure. High-temperature annealing was found to increase the lattice parameter and average crystallite size of the cobalt ferrite nanoparticles. The TEM measurements showed that the nanoparticles were monodisperse and spherical in shape. The FTIR results confirmed the single-phase nature of the prepared nanoparticles. The magnetic measurements showed that the nanoparticles were ferromagnetic over a wide temperature range. We have observed that the high-temperature annealing increased both the saturation magnetization and magnetocrystalline anisotropy and decreased the coercivity. We demonstrated that magnetic field induced superparamagnetism can be induced by applying stronger magnetic fields that were able to shift the blocking temperature (TB) down to below room temperature, resulting in a superparamagnetic behavior above TB.

Synthesis, structural characterization, and magnetic properties of Ni–Zn nanoferrites substituted with different metal ions (Mn2+, Co2+, and Cu2+)

Three series of nanocrystalline Ni0.7-xZn0.3MxFe2O4 ferrites (M = Mn2+, Co2+, and Cu2+; x = 0.0, 0.1, 0.3, 0.5, and 0.7) have been synthesized using the citrate method. Several techniques have been used to investigate the influence of the different dopant ions and their doping levels on the structural and magnetic properties of the Ni–Zn ferrites. X-ray diffraction (XRD) analysis confirmed the creation of a single-phase spinel structure. The lattice parameter was found to increase with increasing Mn2+ and Co2+ ion concentrations, but was not altered by adding Cu2+. The density decreased with increasing concentrations of Mn2+ or Co2+, but increased with increasing Cu2+ content. The average particle size estimated from transmission electron microscopy (TEM) images was found to be in the range 21–41 nm, which revealed the manufacture of nanocrystalline ferrites. Two prominent fundamental absorption bands detected in IR spectra between 370 and 570 cm−1 can be ascribed to the intrinsic stretching vibrations of tetrahedral and octahedral complexes. The magnetic properties of the present spinel ferrites were measured by means of a vibrating sample magnetometer (VSM) at room temperature. The measurements showed that the saturation magnetization (Ms) for Ni–Zn–Mn ferrite increased from x = 0.0 to x = 0.3, but then decreased upon doping at x = 0.7, whereas a monotonic increase in saturation magnetization was observed for Ni–Zn–Co ferrite. For Ni–Zn–Cu ferrite, Ms decreased from 54.70 emu/g at x = 0.0–35.4 emu/g at x = 0.1 and then increased with further addition of Cu2+. The variation of Ms with different dopant concentrations can be explained on the basis of Néel's two-sublattice model. Among the investigated series, Ni0.7-xZn0.3CoxFe2O4 nanoferrites achieved high saturation magnetization and coercive field values, indicating that such compositions may find applications in the field of sensors.