Nickel Zinc Ferrite Nanoparticles Research Articles

Entropy optimization in multigrade motor oil based nanofluid: a spectral and sensitivity analysis with particle shape and dispersion effects

PurposeThis study aims to enhance heat transfer efficiency while minimizing friction factor and entropy generation in the flow of Nickel zinc ferrite (NiZnFe2O4) nanoparticles suspended in multigrade 20W-40 motor oil (as specified by the Society of Automotive Engineers). The investigation focuses on the effects of the melting process, nonspherical particle shapes, thermal dispersion and viscous dissipation on the nanofluid flow.Design/methodology/approachThe fundamental governing equations are transformed into a set of similarity equations using Lie group transformations. The resulting set of equations is numerically solved using the spectral local linearization method. Additionally, sensitivity analysis using response surface methodology (RSM) is conducted to evaluate the influence of key parameters on response function.FindingsHigher dispersion reduces entropy production. Needle-shaped particles significantly enhance heat transfer by 27.65% with melting and reduce entropy generation by 45.32%. Increasing the Darcy number results in a reduction of friction by 16.06%, lower entropy by 31.72% and an increase in heat transfer by 17.26%. The Nusselt number is highly sensitive to thermal dispersion across melting and varying volume fraction parameters.Originality/valueThis study addresses a significant research gap by exploring the combined effects of melting, particle shapes and thermal dispersion on nanofluid flow, which has not been thoroughly investigated before. The focus on practical applications such as fuel cells, material processing, biomedicine and various cooling systems underscores its relevance to sectors such as nuclear reactors, tumor treatments and manufacturing. The incorporation of RSM for friction factor analysis introduces a unique dimension to the research, offering novel insights into optimizing nanofluid performance under diverse conditions.

Influence of Zirconium substitution on electrical properties of Nickel-Zinc Ferrites

The Zirconium substituted Nickel Zinc Ferrite nano particles with chemical composition of Ni(0.5-x)Zn(0.5-x)ZrxFe2O4, where the value of x varies from 0 to 0.2, have been synthesized by the sol-gel auto combustion method, using high purity nitrates and fuelling agent citric acid. The structural property was studies from X-ray diffraction spectra. The crystallite size decreases with increase in Zirconium substitution. The electrical property of the same was investigated by studying the dielectric constant, and AC conductivity. There are fluctuations in these properties with variation in Zirconium substitution in Ni-Zn Ferrite.

Impedance characterization of hydrothermally synthesized nickel zinc ferrite nanoparticles for electronic application

This study comprehensively investigates the structural, morphological, dielectric, and conductivity properties of Ni0.5Zn0.5Fe2O4 nanoparticles synthesized through a hydrothermal method, focusing on their suitability for technological applications. The nanoparticles exhibited a cubic structure with an average grain size of approximately 19 nm. The dielectric properties were analyzed with respect to frequency and temperature, showcasing behaviors consistent with Maxwell-Wagner and Koop's theories. The dielectric plane plots, corresponding to the impedance circuit in the Smith Chart, were found to align with the Davidson-Cole relaxation model. Moreover, the conductivity properties adhered to the Jonscher Power law, resembling conductive properties akin to semiconductors in accordance with the band theory. Notably, the s parameter, indicative of the DC conduction mechanism, displayed temperature-dependent variations, suggesting compatibility with the small polar and correlated hopping barrier conduction models. The thermal activation energies of the Ni0.5Zn0.5Fe2O4 nanoparticles at 102, 103, 104, 105, and 106 rad/s frequencies have been recorded at 0.115, 0.141, 0.157, 0.133 and 0.121 eV, respectively. The experimental results strongly suggest that Ni0.5Zn0.5Fe2O4 nanoparticles hold promise as an inspiring material for electronic circuit applications.

INFLUENCE OF DOPING Zn ON H2 SENSING CHARACTERISTICS OF NICKEL FERRITE NANOPARTICLES

In this paper, the synthesized and testing of H2 gas sensors using nickel zinc ferrite NiFe2O4 and Ni0.5Zn0.5Fe2O4 nanoparticles was shown here. The nickel zinc ferrite nanoparticles were synthesized by chemical co-precipitation combine annealed. Characterization of synthesized powders was made using X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analysis. Nano powder resulting from milling was used to prepare gas sensing elements in pellet form. The gas-sensing properties were studied in presence of hydrogen as test gases. The gas response was found to be strongly influenced by the substitute concentration of Zn. A significant high sensitivity of ~ 90% was found for Zn = 0.5 in presence of 500 ppm H2 at an operating temperature of 250 °C.

Effect of Calcination Temperature and Substitution of Erbium on Structural and Optical Properties of Nickel Zinc Ferrite Nanoparticles

A single composition of erbium-doped nickel zinc ferrite Ni0.5Zn0.5Fe1.95Er0.05O4 is synthesized by the sol-gel autocombustion process. The prepared composition was divided into five equal parts. One of the parts was an as-prepared sample, and remaining four other parts were calcinated at 600, 700, 800, and 900 ∘C to investigate the variation in structural and optical properties with the calcination temperature. The structural characterization was performed using XRD and SEM. Optical properties were analyzed using FTIR and UV-Visible spectral data. XRD patterns confirm the spinel cubic crystal structure and the Fd3m space group. The crystallite size was minimum for the as-prepared sample (17.9452 nm), and the crystallite size was maximum for the sample calcinated at 900 ∘C (29.8481 nm). SEM images revealed the grain size in the interval from 55.38 nm to 177.73 nm, and certain nanotubes were formed in the sample calcinated at 800 ∘C. Optical energy band gap was observed in the interval from 5.556 eV to 3.969 eV. All these testifies to the variations in structural and optical properties of Ni0.5Zn0.5Fe1.95Er0.05O4 with the calcination temperature.

Simultaneous effect of magnetic nanoparticles additive and noble metal coating on carbonyl iron-based magnetorheological fluid

Magnetorheological (MR) fluid is an intelligent fluid that is strongly influenced by an external magnetic field. These fluids are prepared by introducing micron-sized magnetic particles such as carbonyl iron into nonaqueous fluids. The main challenge in those systems containing these fluids such as shock absorbents and abrasive fluids is the instability and sedimentation of magnetic particles in the base fluid. The main aim of the study is to provide stable carbonyl iron (CI)-based magnetorheological fluids with desired efficiency and as much yield stress. In this context, we synthesized Ni-Zn ferrite nanoparticles as additives via high-energy ball milling. This is followed by coating the pristine CI particles with silver via a green-assisted coprecipitation method, using honey as a reducing agent to convert AgNO3 to Ag nanoparticles. The as-produced samples were characterized by the means of XRD, FTIR, FESEM, and TEM. Four types of prepared MR fluids were a CI based, ferrite nanoparticles additive-CI-based MR, Ag-coated CI-based MR, and a combination of the second and third states in the presence of poly alpha olefin oil as the carrier liquid and oleic acid as surfactant agent. The results revealed that the density of the Ag-coated CI was reduced to almost half the density of pristine CI particles. Furthermore, the results of the rheology test on CI-based and CI/Ni Zn ferrite MRs showed an increase in yield stress from 38,000 Pa to 46,000 Pa due to the presence of nickel-zinc ferrite particles. However, magnetorheological fluids based on carbonyl iron particles coated with silver nanoparticles showed a decrease in yield stress (29,700 Pa) because the magnetic property of CI particles has decreased by coating. Magnetorheological fluid based on carbonyl iron particles coated with silver nanoparticles and additive of nickel-zinc ferrite nanoparticles had yield stress similar to magnetorheological fluid based on iron carbonyl particles (38,000 Pa) but with more stability from 55% to 70%.

Band gap and pseudocapacitance of Gd2O3 doped with Ni0.5Zn0.5Fe2O4

Herein, we present a detailed study of the structural, optical, and electrochemical responses of Gd2O3 doped with nickel zinc ferrite nanoparticles. Doping of Ni0.5Zn0.5Fe2O4 nanoparticles to Gd2O3 powder was done through thermal decomposition at 1000 °C. The average grain size of the mixture was determined to be approximately 95 nm, and phases of cubic Gd2O3, GdO, and orthorhombic prisms of GdFeO3 were identified. The focused ion beam energy dispersive x-ray spectrum (FIB-EDX) mapping results clearly show the morphology of the particles with Gd and Fe as the dominant elements. The structural data were compared with the spectroscopic measurements confirming the formation of multiple phases of oxides and ferrites. The measured optical band gap is significantly redshifted to 1.8 eV and is close to that of nitride compounds of gadolinium metal. The measured specific capacitance was almost 7 Fg−1 at a current density of 1 Ag−1, showing a small drop of 27% when the current density is increased to 10 Ag−1. Cyclic voltammetry (CV) plots of the ferrite doped Gd2O3 electrode at a scan rate of 5 to 100 mV s−1 indicate the pseudocapacitive nature of the material.

Redshift of the optical gap in ferrite doped Gd2O3

We report the measurement of the optical bandgap in ferrite doped Gd2O3. Doping of the nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles to Gd2O3 powder was done through thermal decomposition of the mixture at 1000 °C. The average grain size of the thermally decomposed mixture was determined to be around 95 nm and contained phases of cubic Gd2O3, GdO, and orthorhombic prisms of GdFeO3. The imaginary part of the complex dielectric function was calculated from the absorbance measurements that showed an optical bandgap at 1.8 eV. The observed value of the fundamental energy gap is on average 4.0 eV smaller than suggested by early experiments. A model for the ferrite doped Gd2O3 was constructed to suggest that the Ni, Zn, and Fe atoms occupy Gd sites in the Gd2O3 lattice. A new band at Γ point is formed due to the hybridization of the atomic orbitals of dopant and Gd3+ that shifts the fundamental absorption edge to the red part of the photon energy spectrum. Despite having a high density of negatively charged carriers contributed by the dopant, the onset of the direct interband transitions is clearly resolved.

Polysulfone/Chitosan membranes with inorganic nanoparticles

Photovoltaic solar energy has been widely used as an alternative energy source. Composite materials combine the properties of organic polymers, including flexibility and easier processing, with those of inorganic compounds, such as thermal and chemical stability. These characteristics are advantageous to produce materials for organic solar cells. This work aimed to synthesize by casting method and characterize the structure, morphology, chemical, and thermal properties of composite membranes of polysulfone and chitosan (PSF/CS) incorporated with different masses of nickel-zinc ferrite nanoparticles (NZFN) and magnetite nanoparticles (MN). PSF/CS composite membranes incorporated with inorganic nanoparticles were uniform and transparent, evidencing a good dispersion of the nanoparticles and the homogeneity of the synthesized material. The addition of inorganic nanoparticles increases the stability and efficiency of organic substrates making them suitable for different applications in renewable energy systems, such as organic photovoltaic solar cells.

Synthesis of Nickel-Zinc Ferrite Nanoparticles by the Sol-Gel Auto-Combustion Method: Study of Crystal Structural, Cation Distribution, and Magnetic Properties

Spinel ferrite nanocomposites of Ni1–xZnxFe2O4 (x = 0.25 and 0.75) were synthesized by sol-gel auto-combustion and annealed between 250°C and 1000°C. A single-phase spinel structure was found through X-ray diffraction (XRD). The crystallite size is in the range of 17.55–66.98 nm, and lattice parameters are in the range of 8.351–8.434 Å. X-ray analysis revealed a slight shift of the peaks towards shorter angles when the zinc concentration increased from 0.25 to 0.75. XRD measurements revealed the metal ion distribution in the spinel ferrite system. For each sample, XRD data were used to compute structural characteristics such as lattice spacing, lattice constant, crystallite size, oxygen position parameter, tetrahedral and octahedral ionic radii, and bond lengths. Energy dispersive spectroscopy (EDS) spectra and field emission-electron scanning microscope (FESEM) were used to evaluate the elemental content and morphology. EDS analysis confirmed the presence of expected elements in the samples and confirmed the high doping rate of more than 180% of Zn ions in Ni ferrite. The evaluated particle sizes were determined to be 79.2 and 118.4 nm for zinc content of 0.25 and 0.75, respectively. The nearly spherical shape of the nanoparticles was shown in the transmission electron microscope (TEM). The magnetic moment, remanent, coercivity, and saturation magnetization were calculated by using vibrating sample magnetometer (VSM) results. The saturation magnetization magnitudes showed the influence of cation distribution.

Microstructure, phase, magnetic properties, and electromagnetic wave absorption of graphene oxide – Ni0.7Zn0.3Fe2O4 – Al2O3 aerogel

In this work, an ultralight nanocomposite of graphene oxide aerogels as a matrix and nickel-zinc ferrite (Ni 0.7 Zn 0.3 Fe 2 O 4 ) nanoparticles as a second phase for the absorption of electromagnetic waves in the frequency of 1–18 GHz were fabricated by the hydrothermal - freeze-drying method. α-Al 2 O 3 nanoparticles were used for further impedance matching for applications in electromagnetic wave absorption. XRD, SEM, EDS, and VNA analyses were used to characterize the sample. The effects of the amount of Ni 0.7 Zn 0.3 Fe 2 O 4 (NZF) nanoparticles (GO: NZF volume percent ratio = 5:1 and 2:1) on the absorption of electromagnetic waves were investigated.

Tunable Optical Bandgap of Gadolinium Substituted Nickel-Zinc Ferrite Nanoparticles-Effect of Calcination Temperature on Its Optical Parameters

The gadolinium substituted nickel-zinc ferrite nanoparticles of the composition, Ni0.5Zn0.5Gd0.05Fe1.95O4 were prepared using sol-gel method. In order to study the effect of calcination temperature on the optical parameters, the prepared powder was divided into five parts. The first part was taken as the as-prepared sample and the remaining four parts were calcinated at different temperatures, 600°C, 700°C, 800°C & 900°C. The X-ray diffraction patterns revealed the formation of cubic spinel structure with single phase and Fd3m space group. The crystallite size was increased from 11.75 nm to 18.13 nm as the calcination temperature increased from 600 to 900°C whereas as-prepared sample exhibited 17.61 nm. The dislocation density was decreased from 7.243 × 10-3 to 3.042 × 10-3 nm-2 as the calcination temperature increased from 600°C to 900°C. The micro strain was decreased from 10 × 10-4 to 6.452 × 10-4 as the calcination temperature increased from 600°C to 900°C. The characteristic absorbance peaks were obtained at 255.2 nm for the ferrite nanoparticles of as-prepared and calcinated at 600°C and 800°C whereas it was obtained as 252.8 nm for the sample calcinated at 700°C and there was no such characteristic peak in UV-visible range for the sample calcinated at 900°C; it is expected in the below 200 nm region. The optical energy gap was calculated using Kubelka-Munk equation based on Tauc’s plot and found in the range 4.100 eV to 5.389 eV. The lowest energy gap of 4.100 eV exhibited by the sample calcinated at 700°C and the highest energy gap of 5.389 eV by the sample calcinated at 900°C. It is concluded that the tunable band gaps can be obtained with varying calcination temperature.

Effect of calcination and surface functionalization of nanoparticles on structural, magnetic and electrical properties of polyaniline Ni0.5Zn0.5Fe2O4 nanocomposites

The present work explored the electromagnetic polyaniline-nanocomposites materials using calcined and polydopamine functionalized nickel-zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4 ) nanoparticles for adjustment over the magnetic and electrical properties. The properties of the composites were analysed by XRD, HRTEM, Raman, DRS, TGA and VSM techniques. The analytical results showed that the crystallinity and particle size greatly depend on calcination and surface functionalization using dopamine. The crystallization, thermal properties, and saturation magnetization increased by the calcination of nanoparticles, whereas dopamine coating decreased these properties. The dopamine coated nanoferrites nanocomposites have shown the best electrical and electrochemical properties. The dopamine coating of nanoferrites has improved the optical properties owning to effective surface functionalization due to the transfer of the cations on the surface as clear from the FTIR and Raman spectrum. The increase in DC conductivity of the polyaniline nickel zinc ferrite nanocomposites on increasing temperature indicates their semiconducting features. The ionic and DC conductivity of polyaniline nanocomposites can be controlled by tuning the properties of reinforcing nanoparticles through calcination and dopamine coating. All of the findings display the use of polyaniline nanocomposites for energy storage devices and other applications. • Calcination and dopamine functionalization of nickel zinc nanoferrites were carried out. • Dispersion stability of nanoferrites was achieved by polydopamine coating. • Structural, thermal and physiochemical properties of polyaniline nanoferrite composites were investigated.

Study the impact of different preparation methods on the structural and dielectric properties of nickel-zinc ferrite

In the current study, nickel-zinc ferrite nanoparticles Ni (1-x) ZnxFe2O4 (X= 0, 0.25, 0.50, 0.75, 1) have been arranged by sol-gel auto combustion and common chemical precipitation methods, The samples were described by x-ray (XRD) deflection, Fourier converts Infrared Spectroscopy (FTIR), dielectric perpetual and dielectric loss element. the XRD analysis confirms the cubic lone phase spinel configuration for all the synthesized materials. Average crystalline size is estimated of the (311) peaks of the x-ray diffractogram using Scherrer’s formulation institute in the range 38.90 to 37.71 nm for sol-gel auto burning method and from 18.61 to 23.41 nm for co-precipitation method. The Fourier transform infrared spectroscopy was studied so as to assert the construction of the spinel phase and to recognize the kind of carbon remaining in the samples. The dielectric fixed and the dielectric loss factor were measured in the range between 50 Hz – 3 MHz at room temperature were located to be reduced with a rise in regularity.

Enhanced Transport Critical Current Density of Tl-1212 Bulk Superconductor Added with Nickel-Zinc Ferrite Nanoparticles

High temperature superconductor Tl-1212 with nominal starting composition (Tl0.85Cr0.15)Sr2CaCu2O7-δ was prepared with high purity oxide powders using a solid state reaction method. Small amounts of nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) at compositions 0.01, 0.02, 0.05 and 0.10 wt. % were added into Tl-1212 superconductors. The effect of Ni0.5Zn0.5Fe2O4 nanoparticles’ addition on the critical temperature (Tc), transport critical current density (Jc), phase formation, and morphology was studied. The samples were characterized using electrical resistance measurement, transport critical current density measurement, powder X-ray diffraction method (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Zero-resistance critical temperature (Tc-zero) was found to rise from 97 K to 99 K with increasing Ni0.5Zn0.5Fe2O4 nanoparticles concentration. The highest value recorded for transport critical current density (Jc) was 3,120 mA/cm2 at 77 K, which exhibited by sample with 0.02 wt. % of Ni0.5Zn0.5Fe2O4 nanoparticles. All samples showed a dominant Tl-1212 phase and exhibited tetragonal lattice structure in the P4/mmm space group. SEM micrographs showed close-packed microstructure with low porosity. EDX mapping showed that Ni0.5Zn0.5Fe2O4 nanoparticles were well distributed in the Tl-1212 samples. This study demonstrated that Ni0.5Zn0.5Fe2O4 nanoparticles have functioned as effective flux pinning centers to Tl-1212 superconductors and thus significantly enhanced its Jc.

A study of uncoated and coated nickel-zinc ferrite nanoparticles for magnetic hyperthermia

The paper describes how to arrive at the required characteristics suitable for the study of magnetic hyperthermia in a nanoferrite. The composition selected for the study, Ni0.60Zn0.35Fe2.05O4 was synthesized by sol-gel process with an adequate control on its particle size using a chelating agent, polyethylene glycol (PEG). Nanoparticles with mean particle sizes in the range 3.6–8.2 nm were obtained by annealing the as-prepared powder at different temperatures. Identification of single phase spinel structure, particle size determination and magnetic properties of all the samples were made available with X-ray diffraction, Transmission electron microscopy, and Vibration sample magnetometer. The single domain nature of the nanoparticles was established from the particle size dependence of the coercivity. The superparamagnetic behaviour of two annealed samples having a mean particle sizes 3.6 nm and 4.4 nm was established from the temperature dependence of the field cooling and zero field cooling magnetization curves. The observed higher blocking temperature (below room temperature) for smaller particles was attributed to interactions between the particles in the powder samples. The effect of interparticle interactions on heating efficiency was examined by comparing the specific absorption rate (SAR) of nanoparticles dispersed in water at different concentrations. The higher zeta potential values of citric acid coated nanoparticles were pronouncing their long time stability in water with increased SAR and cell viability as compared to their uncoated counterparts. Interestingly, the results of water based citric acid coated nanoparticles assure that the material would be suitable as magnetic mediator for magnetic hyperthermia application.

Tunable heat generation in nickel-substituted zinc ferrite nanoparticles for magnetic hyperthermia.

We report a high-performance magnetic nanoparticle as a hyperthermic agent under low applied field and frequency. CTAB (cetyltrimethylammonium bromide)-coated NixZn1−xFe2O4 nanoparticles of average particle size < 25 nm with various stoichiometric ratios were successfully synthesized using a co-precipitation technique. Characterization results indicate a close interaction of CTAB ions with the surface metal ions resulting in a cation distribution deviating from their equilibrium positions. Magnetic measurements were done at 300 K and 5 K using a superconducting quantum interference device. Saturation magnetization gradually increases with increasing substitution of Ni2+ ions with Zn2+ ions, attributed to the cation distribution and high super-exchange interaction between the A- and B-sites. The average size of the nanoparticles is estimated to be <10 nm with a magnetically dead layer (>1 nm @ 300 K), reflecting the effect of CTAB coating on the surface of the nanoparticles. The magnetocrystalline anisotropy (Keff), obtained from the law of approach to saturation, is inversely proportional to the Ms value. The increasing incorporation of Ni2+ ions in the lattice system is found to influence various structural parameters, which is reflected in the magnetic performance of the nanoparticles. A specific absorption rate of 347 W g−1 and intrinsic loss power of 4.6 nH m2 kg−1 was attained with a minimal concentration of 2 mg ml−1 in a very short time period of 1.5 min in Ni0.75Zn0.25Fe2O4 nanoparticles.

Synthesis and Characterization of Praseodymium Doped Nickel Zinc Ferrites using Microemulsion Method

Spinel ferrites nanoparticles are plays important role in our daily life. Praseodymium doped Nickel Zinc Ferrite Nanoparticles having general formula Ni0.3Zn0.7PrxFe2-xO4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) were synthesized by microemulsion method. X-Ray diffraction (XRD) was used to find different parameters of crystalline size. The development of the FCC spinel structure was observed by XRD data. The most intense peak of the XRD was identified at 2?=35º.From Debye sherrer's formula, calculated the crystalline size 15nm to 29nm ranges. The lattice constant calculations are decreased with the doping of Praseodymium (Pr3+) contents. The x-ray density increases as the concentration of Praseodymium (Pr3+) doping increases, Because Praseodymium (Pr3+) ion has a greater molar weight than Fe3+ ion. The Absorption band spectra are analyzed by using Fourier Transform Infrared spectroscopy (FTIR).The absorption bands ?1 is known as octahedral stretching bands were found to be in the range of 414 cm-1 and ?2 is the tetrahedral stretching band were found to be in the range of 530cm-1.Dielectric properties of Praseodymium doped Nickel-Zinc Ferrite were measured with impedance Analyzer in the frequency of 1 MHz to 3 GHz range. When Pr3+content concentration increases, the dielectric characteristics, such as dielectric constant, dielectric loss, and tangent loss were also decreased. These measured dielectric characteristics showed that these nanomaterials may be used in higher frequencies devices.

Sol-gel derived cobalt containing Ni–Zn ferrite nanoparticles: Dielectric relaxation and enhanced magnetic property study

A systematic study of transitional metal ion doped nickel-zinc ferrite (NZF) nanoparticles with its magnetic properties and conductivity relaxation mechanism are the objectives of this research. We have prepared cobalt doped NZF nanoparticles (NZCo) via a facile chemical route. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analyses suggest the formation of single phase nearly spherical nanoparticles around 60 nm in size. UV–Vis study reveals the redshift of the optical band gap for doped samples. Estimation of particle size using the effective mass model agrees well with TEM/XRD results. The electrical modulus spectra have been analyzed using Harvilliak-Negami model function. Migration energy has been found to be the minimum for 10 mol % doped sample. Frequency-dependent modulus spectra have been converted to time domain data and the relaxation process shows Kohlrausch–Williams–Watts (KWW) type behavior. Carrier motion inside the lattice has been found to be strongly correlated. Room temperature magnetization curve shows that very weak AFM/PM contribution and strong FM interaction inside the system as well as non-collinear spin arrangements between interstitial sites. Law of Approach (L.A.) analysis of the AFM/PM part subtracted hysteresis curve delineates the enhanced magnetic properties such as saturation magnetization, anisotropy constant and coercivity. Multi-functional materials of such kind with optimum behavior at specific doping percentages can be fruitful for electronic industries.

Effect of cation distribution on the structural and dielectric properties of $${\mathrm{N}\mathrm{i}}_{0.5-x}{\mathrm{C}\mathrm{o}}_{x}{\mathrm{Z}\mathrm{n}}_{0.5}{\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{4}$$ (0.0 ≤ x ≤ 0.5) ferrites

Cobalt-substituted nickel–zinc ferrite nanoparticles, i.e., $${\mathrm{N}\mathrm{i}}_{0.5-x}{\mathrm{C}\mathrm{o}}_{\mathrm{x}}{\mathrm{Z}\mathrm{n}}_{0.5}{\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{4}$$ (0.0 ≤ x ≤ 0.5) were prepared by the sol–gel method. X-ray diffraction patterns revealed that the prepared samples crystallized in cubic spinel structure, whereas the scanning electron microscopy study exhibited a change in the morphology of grains due to Co2+ substitution. 57Fe Mossbauer measurements suggested that the presence of iron is only in the Fe3+ oxidation state which is randomly distributed over the tetrahedral and octahedral sites. However, the fraction of Fe3+ ions present at the octahedral site strongly depends on the unusual site preference of substituted Co2+ ions for the tetrahedral site. Thus, the cationic distribution between both the sites altered with increasing Co2+ substitution. Significant enhancement in the resistive properties is found with increasing Co2+ substitution and the obtained values are ~ 104 times higher than that reported for their bulk counterparts. This improvement in the resistive properties is elucidated based on changes in the microstructure and cation redistributions due to Co2+ substitution. Here, we report that the colossal resistivity (3.82 × 1010 Ω cm) and diminished tangent loss (~ 0.01) for the sample with x = 0.2 make this composition interesting for high-frequency applications.