Ni Ferrites Research Articles

A study of the structural and morphological properties of Ni–ferrite, Zn–ferrite and Ni–Zn–ferrites functionalized with starch

Zinc–ferrite, nickel–ferrite and mixed nickel–zinc ferrites were successfully synthesized via the thermal decomposition method from acetylacetonate complexes. To control the particle size and enhance dispersibility in an aqueous medium, starch, a natural and biocompatible compound, was used for the first time for coating such magnetic powders. X-ray powder diffraction (XRPD) was performed to study the structural properties of all samples. The presence of a single-phase spinel structure as well as the cation distribution in both sites of all investigated magnetic powders was confirmed. The values of unit cell parameters obtained from the results of the Rietveld analysis decreased, while the average crystallite size increased with increasing Ni2+ content. The average microstrain parameters unambiguously showed a change in the spinel structure with cation distribution. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses were also utilized to characterize the synthesized materials, corroborating the XRPD data. The obtained results indicated that functionalization by starch was successfully achieved.

Dielectric and magnetic properties of high porous Gd+3 substituted nickel zinc ferrite nanoparticles

We report on the synthesis and characterization of Gd+3 substituted Ni-Zn nano ferrites (Ni0.6Zn0.4GdyFe2−yO4; y = 0, 0.1, 0.15, and 0.2) via low-temperature citrate gel auto-combustion method. The structural studies carried out by PXRD revealed a decrease in the lattice constant and crystallite sizes upon Gd+3 substitution with low concentration but increases with further increase in the concentration. We found the porosity of the samples decreases linearly as a function of Gd+3 concentrations. Well defined spherical grains with a higher porosity of the samples are confirmed by FESEM analysis. With an increase in the Gd+3 concentrations, the dielectric constant increased up to five folds in the magnitude. The contribution of grain boundary and other factors on the electrical properties was revealed by impedance spectroscopy. The reduced remanence ratios showed in the magnetic hysteresis imply the charge in change in the magnetic properties upon the substitution of Gd+3 in the prepared ferrite.

INFLUENCES OF CATION DISTRIBUTION OF ZINC SUBSTITUTED ON INVERSE SPINEL NICKEL FERRITE NANOPARTICLE FOR SUPERPARAMAGNETIC APPROACH

Sol–gel method has been employed to prepare Ni–Zn ferrite with chemical formula Ni[Formula: see text]ZnxFe2O4 where [Formula: see text] 0, 0.1, 0.2, 0.3, 0.4 and 0.5. The structural Ni–Zn ferrite was studied via the X-ray diffractometer (XRD) pattern. X-ray analysis showed that there is a small shift in peaks towards shorter angles which increases with the concentration of zinc. Experimental values of lattice constant was varied from 8.34 of Ni ferrite to 8.397[Formula: see text]nm for Ni–Zn ferrite. The crystallite size of Ni ferrite was 83[Formula: see text]nm which is decreasing with substituted Zn to it and became 43[Formula: see text]nm at [Formula: see text]. Therefore, the superparamagnetic behavior appears with substitution of Zn to Ni ferrite. The saturation magnetization, remiensis, coersivity, magnetic moment and anisotropy constant were calculated according to hysteresis loop using the result of vibrating sample magnetometer (VSM). The effect of cation distribution appeared clearly through the saturation magnetization value which was 46.8[Formula: see text]emu/gm for nickel ferrite and increased to an optimum value (59.64[Formula: see text]emu/gm) at [Formula: see text].

Structural and magnetic properties of Ni0.8M0.2Fe2O4 (M = Cu, Co) nano-crystalline ferrites

Abstract Nano-crystalline nickel ferrites are interesting materials due to their large physical and magnetic properties. In the present work, two kinds of spinel ferrites Ni0.8M0.2Fe2O4 (M = Cu, Co) are synthesized by using sol-gel auto-combustion method and the results are compared with NiFe2O4. The structural properties of synthesized ferrites are determined by using X-ray powder diffraction; scanning electron microscope and Fourier transform infrared spectroscopy. The cation distribution obtained from X-ray diffraction show that cobalt/copper occupies only tetrahedral site in spinel lattice. The lattice constant increases with the substitution of cobalt/copper. The structural parameters like bond lengths, tetrahedral and octahedral edges have been varied with the substitution. The microstructural study is carried out by using SEM technique and the average grain size is increased with nickel ferrite. The initial permeability (μi) is improving with the substitution. The observed g-value from ESR is approximately equal to standard value.

Microstructural, magnetic and electrical properties of Zn0.4M0.3Co0.3Fe2O4 (M = Ni and Cu) ferrites synthesized by sol–gel method

A comparative study of microstructural, magnetic and electrical properties of Zn0.4Ni0.3Co0.3Fe2O4 (ZNCFO) and Zn0.4Cu0.3Co0.3Fe2O4 (ZCCFO) ferrites prepared using sol–gel method have been investigated in this work. X-ray diffraction results indicate that samples have cubic spinel type structure ( $$Fd\bar {3}m$$ space group). Lattice constant, average grain size and X-ray density are higher for ZCCFO than those of ZNCFO. The magnetic parameters such as M s , H c , and M r were found to decrease with the substitution of Ni by Cu. The electrical properties of the samples have been studied using impedance measurements as a function of frequency and temperature. The substitution of Zn–Co ferrite with Cu leads to improve its conductivity that its substitution with Ni. The behaviors of imaginary part of permittivity and loss tangent have been investigated using Maxwell–Wagner’s model and Koop’s theory. The electrical modulus study reveals the presence of the non-Debye type of dielectric relaxation in our samples. Close values of activation energy for dc conduction (E dc ) and for conductivity relaxation (E Mʺ ) were found confirming that the relaxation process and electrical conductivity are attributed to the same defect. Nyquist representations (Z″ vs. Zʹ) were plotted and their characteristic behaviors were analyzed in terms of electrical equivalent circuit.

Synthesis and Properties of Ni-doped Goethite and Ni-doped Hematite Nanorods

Ni-doped goethite (α-FeOOH) nanorods were synthesized from mixed Fe(III)-Ni(II) nitrate solutions with various Ni/(Ni+Fe) ratios (0, 5, 10, 20, 33 and 50 mol % Ni) by hydrothermal precipitation in a highly alkaline medium using the strong organic alkali, tetramethyl¬ammonium hydroxide (TMAH). Ni-doped hematite (α-Fe2O3) nanorods were obtained by calcination of Ni- doped goethite nanorods at 400 °C. The Ni2+- for-Fe3+ substitution in goethite and hematite was confirmed by determination of the unit cell expansion (due to the difference in the ionic radii of Fe3+ and Ni2+) using XRPD and determination of the reduction of a hyperfine magnetic field (due to the difference in magnetic moments of Fe3+ and Ni2+) using Mossbauer spectroscopy. Single- phase goethite nanorods were found in samples containing 0 or 5 mol % Ni. A higher Ni content in the precipitation system (10 mol % or more) resulted in a higher Ni2+-for-Fe3+ substitution in goethite, and larger Ni-doped goethite nanorods, though with the presence of low crystalline Ni-containing ferrihydrite and Ni ferrite (NiFe2O4) as additional phases. Significant changes in FT-IR and UV-Vis-NIR spectra of prepared samples were observed with increasing Ni content. Electrochemical measurements of samples showed a strong increase in oxygen evolution reaction (OER) electrocatalytic activity with increasing Ni content.

Effect of Zn substitution on the structural and magnetic properties of nanocrystalline NiFe2O4 ferrites

Nanocrystalline Ni1−xZnxFe2O4 (where, x = 0.0, 0.2, 0.4, 0.6, 0.8 & 1) samples were synthesized through solution combustion technique using oxylyl de-hydrazide (ODH) as a fuel and the effect of dopant and its concentration on the structural and magnetic properties was investigated. As-prepared samples were characterized using different characterization techniques such as, XRD, SEM-EDS, TEM and Raman spectroscopy for their phase-purity, crystallinity, surface morphology and elemental composition; also magnetic properties were investigated through EPR, Mossbauer spectroscopy and vibrating sample magnetometer (VSM). Rietveld fitted XRD and Raman studies confirm the formation of cubic spinel structured ferrites and substitution of Zn ion at Ni site without formation of impurity phases. No other structural changes were observed and the structure remains in cubic phase with increase of Zn concentration. SEM and TEM micrographs reveal that the particles are agglomerated and the particles size were found in the nano range. Also good stoichiometric composition was observed in all the compositions of Zn substituted Ni ferrite samples. Magnetic measurements (VSM) reveal that pure Ni ferrites exhibits soft magnetic behaviour. Further the ferromagnetic behaviour suppressed with the substitution of diamagnetic Zn ion and with increase of its concentration in Ni ferrites, which was further evidenced in the Mossbauer spectroscopic results. At room temperature, electronic paramagnetic resonance spectra exhibits a broad resonance signal with Lande's g factor varies from 2.23 to 1.95 with increase in Zn content, which is attributed to spin exchange interactions between Fe3+, Ni2+ and Zn2+ ions also asymmetric EPR spectra was observed. The investigated results show that, Zn substitution has greater impact on the magnetic properties of Ni ferrites due to the diamagnetic nature of Zn, which inturn alters the cationic distribution and the exchange interactions between Ni-Fe and Fe-Fe.

Influences of Ni2+ on magnetic property and dielectric property in spinel structure of Mg ferrite (Mg1−xNixFe2O4)

In this present work, we studied the effect of Nickel substitution on the structural, electrical and magnetic property of NixMg1−xFe2O4 (x = 0.00, 0.10, 0.20 and 0.30) synthesized by sol–gel auto combustion technique and characterized by various method such as the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM) and dielectric properties. The XRD pattern reveals the single phase cubic spinel structure and the lattice parameters values of range 8.368–8.394 A were observed. Surface morphology and particle sizes were studied by using FE-SEM. The dielectric constants have been ascribed to Maxwell–Wagner and Interfacial theory in agreement with Koop’s phenomenological theory. The resistance values decrease with increasing temperature which showed negative temperature coefficient. The decreasing tendency of saturation magnetization was owing to the enhancement in the substitution of Nickel cations in Magnesium ferrites. The coercivity value increases under the control of Nickel content in Mg ferrites. The behavior of Mg–Ni ferrite is ferromagnetic at room temperature which is applied in various technological and industrial areas like magnetic sensor, high frequency device and recording tape.

Understanding the impacts of Al+3-substitutions on the enhancement of magnetic, dielectric and electrical behaviors of ceramic processed nickel-zinc mixed ferrites: FTIR assisted studies

Al-incorporated Ni-Zn ferrites (Ni0.65Zn0.35AlxFe2−xO4, where x=0, 0.03, 0.06, 0.09, 0.12) synthesized via standard ceramic technology were investigated for their structural, magnetic, dielectric, and electrical properties. Al substitution plays a remarkable role in refining the structural features and other properties of the ferrite particles. The bulk density, porosity and lattice parameters of Ni-Zn ferrites were decreased with increased Al-content while the X-ray density was reduced. XRD patterns confirmed the single-phase cubic spinel structure of the ferrites particles. The room temperature infra-red spectra shows the features of higher and lower energy bands detected at ν2∼400–405cm−1 and ν1∼590–594cm−1, respectively corresponded to tetrahedral (T-band) and octahedral vibration (O-band) complexes that also confirm the formation of Ni-Zn inverse spinels. The real part of the complex initial permeability, Curie temperature, ac resistivity and loss tangent of the ferrite powders were reduced while the quality factor was enhanced with the subsequent Al-substitution. The observed bi-layer space charge polarization feature was believed to correlate the normal dielectric behavior of Al-substituted Ni-Zn matrix.

Synthesis and Characterization of Hybrid Ni0.5Zn0.5Fe2O4@SiO2/chitosan

In this work we evaluate the use of silane agent 3-aminopropyltrimethoxysilane and biopolymer chitosan to functionalize ferrites Ni0.5Zn0.5Fe2O4 using the solvent evaporation method aiming at obtaining hybrid material Ni0.5Zn0.5Fe2O4@SiO2/chitosan for use as a biosensor. The nanoparticles before and after the functionalization showed the major phase Ni0.5Zn0.5Fe2O4. The FTIR spectra showed absorption bands characteristic of CO, axial deformation of CN and SiO band from the silane agent which proved functionalization. The functionalization of ferrite Ni0.5Zn0.5Fe2O4 with chitosan caused a 36.36% reduction in saturation magnetization as compared with ferrite synthesized, however it maintained the ferrimagnetic characteristic indicating to be a promising material for the use in biotechnological applications as for example in magnetic biosensors.

Structural and electro-magnetic properties of low temperature co-fired BaSrTiO3 and NiCuZn ferrite composites for EMI filter applications

For the application of electro-magnetic interference filter, magneto-electric composites of spinel ferrite (Ni0.25Cu0.20Zn0.55)Fe2O4 and dielectric (Ba0.75Sr0.25)TiO3 have been prepared by a standard ceramic technique and the effects on structural, dielectric and electro-magnetic properties have been investigated. Ferrite-dielectric mixed powder is uniaxially pressed into toroids and pellets. Specimens are sintered at 950 °C. Powder X-ray diffraction (XRD) indicates a mixed phase of composites with spinel and perovskite phase. The microstructural analysis shows dense structure with some porosity. The variations in dielectric constant and loss tangent with frequency are also studied. The dielectric constant of composite continuously decreases and permeability increases with increasing ferrite content. Observations of P–E hysteresis loops and M–H hysteresis loops, respectively, confirm the dielectric and ferromagnetic nature of the composite samples.

Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites

In our present work, we have synthesized a series of Cd-Zn doped nickel ferrite ((Cd0.5−xZnx)Ni0.5Fe2O4; x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) through standard chemical co-precipitation method to study the influence of diamagnetic ions (Cd, Zn) on the magnetic properties of ferrites. XRD and Raman spectroscopy were employed for the structural characterizations. The refinement of the X-ray diffractogram data augmented by the Williamson-Hall plots showed the presence of Cd2+ vacancies and a strained crystal structure. The vibrational spectroscopy indicated the presence of lower space-group symmetry and a distorted crystal structure. Magnetic measurements showed the samples possessed low magnetic anisotropy along with a canted spin structure. The Mössbauer measurements confirmed the cation distribution and gave evidence of super transferred hyperfine interactions arising due to canted spin structure of the system.

The Reflection of Cr/Fe Substitution on the Structural, Magnetic and Photoluminescence Features of Zn–Ni Based Ferrite

In this work, we substituted iron by chromium in the nano-spinel ferrite Ni0.5Zn0.5Fe2O4 (NZF), then we studied how relevant the structure, magnetic, and optical characteristics of the produced samples are changed accordingly. This doping caused a redistribution of Fe, Zn, and Ni ions over tetrahedral and octahedral sites as confirmed from XRD Reitveld analysis. Upon Cr/Fe substitution, a decrease in the lattice parameter occurred accompanied by a decrease in crystallite size of the doped samples. Magnetic measurements indicated the decrease of saturation magnetization by increasing the amount of Cr doping. On the other hand, the coercivity (H c) increases about six times from Cr content x = 0.0 (28.28 Oe) to x = 1.0 (192.25 Oe). Photoluminescence (PL) measurements at 650 nm excitation showed emission peaks arising from Fe3+ transitions, band-to-band transitions, oxygen defect-related emission, and Cr3+ transitions that appeared strongly at heavily doped NZF with Cr. The PL intensity quenches strongly with increasing Cr/Fe ratio due to concentration, mobility, and generation of non-radiative center effects. The band gap energy of the Cr-doped NZF system is red shifted until x = 0.5 and the increases (blue shifted) at x = 0.75.

Microstructural and Magnetic Characteristics of Divalent Zn, Cu and Co-Doped Ni Ferrites

Microstructural and Magnetic Characteristics of Divalent Zn, Cu and Co-Doped Ni Ferrites

The FMR Behaviour of Li–Ni Ferrite Prepared by Hydrothermal Method

Magnetic hysteresis loop and ferromagnetic resonance (FMR) behaviour had been studied by considering the variation of the molar ratio of Li0.5−0.5x Ni x Fe2.5−0.5x O 4 ferrite nanostructure prepared by the hydrothermal method. The parameters of the ferrite nanostructure include coercivity (H c), saturation magnetisation (M s) and magnetic susceptibility. There was low coercivity at x = 0.3, high saturation magnetisation and high susceptibility (χ i) at (x = 0.5). These parameters showed an improvement in their values compared with the samples prepared by conventional methods. The FMR analysis indicated that these samples were lossy materials due to having a broad line width ranging from 800 to 925 G. The FMR lines had asymmetric shapes due to anisotropic broadening and conduction mechanism.

Effect of pH on Structural, Magnetic and FMR Properties of Hydrothermally Prepared Nano Ni Ferrite

AbstractNano nickel ferrite particles were prepared at pH values 1.5, 4, 7, 10, 13 by a hydrothermal method using metal chlorides and NaOH as an oxidant and solution basicity controller. There is a phase transition from hematite to spinel ferrite that begins when the pH reaches 4. The lowest crystallite size (4 nm) was associated with a highest lattice constant (8.345 Å), at pH=4. Whereas maximum crystallite size 64.5 nm corresponds lattice constant of 8.298 Å at pH=10. The highest magnetization (48 emu/g) value was achieved for the sample prepared at pH=7, which at the same time has a lower coercivity. The samples synthesized at pH ≥4 show superparamagnetic behavior owing to its low particle size and to zero field cooling and field cooling measurements. The ferromagnetic resonance (FMR) cavity tests analysis show that the broadened linewidth (770 Oe) and high imaginary permeability or high microwave absorption which is linked to high magnetization and low coercivity of superparamagnetic particles and their aggregation. There was a shift in the resonance field due to internal fields and cation distribution.

Cation distribution and magnetic analysis of wideband microwave absorptive CoxNi1−xFe2O4 ferrites

CoxNi1−xFe2O4 ferrites (x=0, 0.2, 0.4, 0.4, 0.6, 0.8 and 1) were prepared by a sol-gel auto-combustion method. The samples were structurally characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). The XRD patterns confirmed single phase formation of spinel structure. Cation distribution estimated from XRD data suggested the mixed spinel structure of ferrite. The EDX analysis was in good agreement with the nominal composition. The results of FTIR analysis indicated that the functional groups of Co-Ni spinel ferrite were formed during the combustion process. According to FE-SEM micrographs, by addition of cobalt ion the average particle size of substituted nickel ferrite was gradually became smaller from 450nm to 280nm. Magnetic measurement using vibrating sample magnetometer (VSM) showed an increase in saturation magnetization and coercivity by Co2+ substitution in nickel ferrite. For Co0.8Ni0.2Fe2O4 sample, Ms and Hc reaches as high as 93emu/g and 420Oe, respectively. The reflection loss properties of the nanocomposites were investigated in the frequency range of 8–12GHz, using vector network analyzer (VNA). Cobalt substitution could enhance reflection loss of NiFe2O4 ferrite. The maximum reflection loss value of the Co2+ substituted Ni ferrite was ~ −26dB (i.e. over 99% absorption) at 9.7GHz with bandwidth of 4GHz (RL<– 10dB) through the entire frequency range of X-band.

Synergy of Miniemulsion and Solvothermal Conditions for the Low-Temperature Crystallization of Magnetic Nanostructured Transition-Metal Ferrites

Crystalline first-row transition-metal (Mn, Fe, Co, Ni, Cu, and Zn) ferrites were prepared by an unprecedented synergetic combination of miniemulsion synthesis and solvothermal route, pursuing unconventional conditions in terms of space confinement, temperature, and pressure. This synergy allowed for obtaining six different crystalline ferrites at much lower temperature (i.e., 80 °C) than usually required and without any postsynthesis thermal treatment. X-ray diffraction (XRD) revealed that analogous ferrites synthesized by miniemulsion at ambient pressure or in bulk (i.e., from an aqueous bulk solution and not in the confined space of the miniemulsion droplets) either at ambient pressure or under solvothermal conditions did not result in comparatively highly crystalline products. To follow the structural evolution at local level as a function of reaction time and depending on the synthesis conditions, X-ray absorption spectroscopy (XAS) was used to determine the cation distribution in these structures. W...

Impact of Dy on structural, dielectric and magnetic properties of Li-Tb-nanoferrites synthesized by micro-emulsion method

A series of Dy-doped Li–Ni ferrites of the following composition Li0.5Ni0.48Tb0.02DyxFe2−xO4 (0.2≤x≥0) was synthesized by the microemulsion method. The X-ray diffraction (XRD) analysis indicated that Li0.5Ni0.48Tb0.02DyxFe2−xO4nano-crystalline ferrites exhibited the single-phase spinel structure. The lattice parameter was determined by the Nelson-Riley refinement technique and it increased by increasing the Dy contents. The crystallite size was computed from the Debye Scherrer's formula and it was in range from 27 to 40nm. The thermal decomposition process was studied by the thermogravimetric analysis and the annealing temperature observed was 980°C. The real and complex parts of dielectric constant decreases very sharply in the lower frequency region, but in the higher frequency region, the real and complex part of dielectric constant show variable values with Dy contents. The dielectric tangent loss (tanδ) decreases exponentially with Dy contents. The magnitude of the ac conductivity decreases in certain frequency region, as the Dy contents are increased. The possible mechanisms contributing to the above behavior are discussed. The results of these nanocrystalline ferrites are very suitable materials for microwave device applications.

Comparative studies of the dielectric properties of (1−x)BiFeO3-xNi0.8Zn0.2Fe2O4 (x=0.0, 0.2, 0.5, 0.8, 1.0) multiferroic nanocomposite with their single phase BiFeO3 and Ni0.8Zn0.2Fe2O4

BiFeO3 (BFO) and nickel zinc ferrite Ni0.8Zn0.2Fe2O4 (NZFO) were prepared by sol gel and auto combustion route respectively. Stoichiometric proportions were mixed to obtain the multiferroic nanocomposites having the compositional formula (1−x)BiFeO3-x Ni0.8Zn0.2Fe2O4 (x=0.0, 0.2, 0.5, 0.8, 1.0). The phases were confirmed by XRD analyses. SEM micrographs showed the agglomerated nature of the particles with continuous grain growth in all directions. Elemental compositions were confirmed from EDAX studies. FTIR studies showed the stretching and bending vibrations of the various bonds present in the samples. The dielectric properties such as dielectric constant, ε′ and dielectric loss tangent, tanδ were studied for the spinel, perovskite and nanocomposite ferrites. Experimental result shows an increasing trend in the value of dielectric constant in going from spinel to perovskite phase. The frequency dependence of tanδ showed minimum loss for x=0.5 nanocomposite. Possible mechanisms explaining the above results were being discussed.